From 512154b13679d44ff3a3d41c0050078be8c15eed Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 08:50:50 -0700
Subject: [PATCH 1/9] Revert "Fix issue where initial script was not always
 selected in File Explorer (#3400)"

This reverts commit a440224c5b6bea40271dad5e6cad411ffe9e20d1.
---
 .../lib/src/debugger/debugger_controller.dart         | 11 +++--------
 .../lib/src/debugger/program_explorer_controller.dart |  5 ++++-
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/packages/devtools_app/lib/src/debugger/debugger_controller.dart b/packages/devtools_app/lib/src/debugger/debugger_controller.dart
index dabb293c281..3dd0f156496 100644
--- a/packages/devtools_app/lib/src/debugger/debugger_controller.dart
+++ b/packages/devtools_app/lib/src/debugger/debugger_controller.dart
@@ -41,14 +41,7 @@ class DebuggerController extends DisposableController
       _showScriptLocation(ScriptLocation(scriptsHistory.current.value));
     };
     scriptsHistory.current.addListener(_scriptHistoryListener);
-    addAutoDisposeListener(currentScriptRef, () async {
-      if (!programExplorerController.initialized.value) {
-        await programExplorerController.initialize();
-      }
-      if (currentScriptRef.value != null) {
-        programExplorerController.selectScriptNode(currentScriptRef.value);
-      }
-    });
+    programExplorerController.initialize(currentScriptRef.value);
 
     if (_service != null) {
       initialize();
@@ -200,6 +193,8 @@ class DebuggerController extends DisposableController
     // set to null to ensure that happens.
     _scriptLocation.value = null;
     _scriptLocation.value = scriptLocation;
+
+    programExplorerController.selectScriptNode(scriptLocation.scriptRef);
   }
 
   Future<Script> getScriptForRef(ScriptRef ref) async {
diff --git a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart b/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
index a6c1e2f491c..5e44b6d5ff4 100644
--- a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
+++ b/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
@@ -63,7 +63,7 @@ class ProgramExplorerController extends DisposableController
 
   /// Initializes the program structure.
   // TODO(bkonyi): reinitialize after hot reload.
-  Future<void> initialize() async {
+  Future<void> initialize([ScriptRef initialScript]) async {
     if (_initializing) {
       return;
     }
@@ -117,6 +117,9 @@ class ProgramExplorerController extends DisposableController
       this,
       _programStructure,
     );
+    if (initialScript != null) {
+      _selectScriptNode(initialScript, nodes);
+    }
     _rootObjectNodes.addAll(nodes);
     _initialized.value = true;
   }

From 923425d2520f2f3922fd7b5b35f1de4b85899b78 Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 08:51:03 -0700
Subject: [PATCH 2/9] Revert "Show a spinner while loading program outline in
 file explorer (#3399)"

This reverts commit 54cbb7b200728a2522fadec50b5d94e59a5852f8.
---
 .../lib/src/debugger/program_explorer.dart    | 43 ++++++++-----------
 .../debugger/program_explorer_controller.dart |  6 ---
 packages/devtools_test/lib/mocks.dart         |  1 -
 3 files changed, 17 insertions(+), 33 deletions(-)

diff --git a/packages/devtools_app/lib/src/debugger/program_explorer.dart b/packages/devtools_app/lib/src/debugger/program_explorer.dart
index 5df2cfeb9e8..b11e49f13f2 100644
--- a/packages/devtools_app/lib/src/debugger/program_explorer.dart
+++ b/packages/devtools_app/lib/src/debugger/program_explorer.dart
@@ -319,33 +319,24 @@ class _ProgramOutlineView extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    print(controller.isLoadingOutline);
-    return ValueListenableBuilder<bool>(
-      valueListenable: controller.isLoadingOutline,
-      builder: (context, isLoadingOutline, _) {
-        if (isLoadingOutline) {
-          return const CenteredCircularProgressIndicator();
+    return ValueListenableBuilder<List<VMServiceObjectNode>>(
+      valueListenable: controller.outlineNodes,
+      builder: (context, nodes, _) {
+        if (nodes == null || nodes.isEmpty) {
+          return const Center(
+            child: Text('Nothing to inspect'),
+          );
         }
-        return ValueListenableBuilder<List<VMServiceObjectNode>>(
-          valueListenable: controller.outlineNodes,
-          builder: (context, nodes, _) {
-            if (nodes == null || nodes.isEmpty) {
-              return const Center(
-                child: Text('Nothing to inspect'),
-              );
-            }
-            return TreeView<VMServiceObjectNode>(
-              itemExtent: _programExplorerRowHeight,
-              dataRoots: nodes,
-              onItemSelected: onItemSelected,
-              onItemExpanded: onItemExpanded,
-              dataDisplayProvider: (node, onTap) {
-                return _ProgramExplorerRow(
-                  controller: controller,
-                  node: node,
-                  onTap: onTap,
-                );
-              },
+        return TreeView<VMServiceObjectNode>(
+          itemExtent: _programExplorerRowHeight,
+          dataRoots: nodes,
+          onItemSelected: onItemSelected,
+          onItemExpanded: onItemExpanded,
+          dataDisplayProvider: (node, onTap) {
+            return _ProgramExplorerRow(
+              controller: controller,
+              node: node,
+              onTap: onTap,
             );
           },
         );
diff --git a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart b/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
index 5e44b6d5ff4..79c43bdf82b 100644
--- a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
+++ b/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
@@ -28,9 +28,6 @@ class ProgramExplorerController extends DisposableController
   ValueListenable<List<VMServiceObjectNode>> get outlineNodes => _outlineNodes;
   final _outlineNodes = ListValueNotifier<VMServiceObjectNode>([]);
 
-  ValueListenable<bool> get isLoadingOutline => _isLoadingOutline;
-  final _isLoadingOutline = ValueNotifier<bool>(false);
-
   /// The currently selected node.
   VMServiceObjectNode _selected;
 
@@ -152,7 +149,6 @@ class ProgramExplorerController extends DisposableController
   Future<void> refresh() async {
     _objectIdToLibrary.clear();
     _selected = null;
-    _isLoadingOutline.value = true;
     _outlineNodes.clear();
     _initialized.value = false;
     _initializing = false;
@@ -170,11 +166,9 @@ class ProgramExplorerController extends DisposableController
       node.select();
       _selected?.unselect();
       _selected = node;
-      _isLoadingOutline.value = true;
       _outlineNodes
         ..clear()
         ..addAll(await _selected.outline);
-      _isLoadingOutline.value = false;
     }
   }
 
diff --git a/packages/devtools_test/lib/mocks.dart b/packages/devtools_test/lib/mocks.dart
index 853b7146d1f..cf8ec8444ae 100644
--- a/packages/devtools_test/lib/mocks.dart
+++ b/packages/devtools_test/lib/mocks.dart
@@ -714,7 +714,6 @@ class MockProgramExplorerController extends Mock
     when(controller.initialized).thenReturn(ValueNotifier(true));
     when(controller.rootObjectNodes).thenReturn(ValueNotifier([]));
     when(controller.outlineNodes).thenReturn(ValueNotifier([]));
-    when(controller.isLoadingOutline).thenReturn(ValueNotifier(false));
 
     return controller;
   }

From f11e8185e06ce294b4e68fa8411ccb0a41cb1e5f Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 08:51:22 -0700
Subject: [PATCH 3/9] Revert "Hide synthetic classes created by mixin
 applications in outline view (#3398)"

This reverts commit a2669d1373f6a2c09edcd512195ca72f289ae6d9.
---
 .../devtools_app/lib/src/debugger/program_explorer_model.dart | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/packages/devtools_app/lib/src/debugger/program_explorer_model.dart b/packages/devtools_app/lib/src/debugger/program_explorer_model.dart
index b7c598c6c86..be6fa9025f2 100644
--- a/packages/devtools_app/lib/src/debugger/program_explorer_model.dart
+++ b/packages/devtools_app/lib/src/debugger/program_explorer_model.dart
@@ -161,10 +161,6 @@ class VMServiceObjectNode extends TreeNode<VMServiceObjectNode> {
     }
 
     for (final clazz in lib.classes) {
-      // Don't surface synthetic classes created by mixin applications.
-      if (clazz.name.contains('&')) {
-        continue;
-      }
       if (clazz.location.script.uri == uri) {
         final clazzNode = VMServiceObjectNode(
           controller,

From 1a0a0fa690740815754c16fecb895464528e63e9 Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 08:51:32 -0700
Subject: [PATCH 4/9] Revert "Don't scroll code view to top when
 opening/closing file explorer (#3395)"

This reverts commit 577c943191ac0ec51d9931f9ad5dcd3d763cd2ef.
---
 .../lib/src/debugger/codeview.dart            | 30 +++++++------------
 .../lib/src/debugger/debugger_screen.dart     |  2 +-
 2 files changed, 11 insertions(+), 21 deletions(-)

diff --git a/packages/devtools_app/lib/src/debugger/codeview.dart b/packages/devtools_app/lib/src/debugger/codeview.dart
index 673e1a0e25d..411be388f1f 100644
--- a/packages/devtools_app/lib/src/debugger/codeview.dart
+++ b/packages/devtools_app/lib/src/debugger/codeview.dart
@@ -82,10 +82,6 @@ class _CodeViewState extends State<CodeView>
 
   ParsedScript get parsedScript => widget.parsedScript;
 
-  // Used to ensure we don't update the scroll position when expanding or
-  // collapsing the file explorer.
-  ScriptRef _lastScriptRef;
-
   @override
   void initState() {
     super.initState();
@@ -94,7 +90,6 @@ class _CodeViewState extends State<CodeView>
     gutterController = verticalController.addAndGet();
     textController = verticalController.addAndGet();
     horizontalController = ScrollController();
-    _lastScriptRef = widget.scriptRef;
 
     if (widget.initialPosition != null) {
       final location = widget.initialPosition.location;
@@ -150,22 +145,18 @@ class _CodeViewState extends State<CodeView>
       log('LinkedScrollControllerGroup has no attached controllers');
       return;
     }
+
     final location = widget.controller.scriptLocation.value?.location;
     if (location?.line == null) {
-      // Don't scroll to top if we're just rebuilding the code view for the
-      // same script.
-      if (_lastScriptRef?.uri != scriptRef?.uri) {
-        // Default to scrolling to the top of the script.
-        if (animate) {
-          verticalController.animateTo(
-            0,
-            duration: longDuration,
-            curve: defaultCurve,
-          );
-        } else {
-          verticalController.jumpTo(0);
-        }
-        _lastScriptRef = scriptRef;
+      // Default to scrolling to the top of the script.
+      if (animate) {
+        verticalController.animateTo(
+          0,
+          duration: longDuration,
+          curve: defaultCurve,
+        );
+      } else {
+        verticalController.jumpTo(0);
       }
       return;
     }
@@ -191,7 +182,6 @@ class _CodeViewState extends State<CodeView>
         verticalController.jumpTo(scrollPosition);
       }
     }
-    _lastScriptRef = scriptRef;
   }
 
   void _onPressed(int line) {
diff --git a/packages/devtools_app/lib/src/debugger/debugger_screen.dart b/packages/devtools_app/lib/src/debugger/debugger_screen.dart
index d643398a837..d8f4f08a6f0 100644
--- a/packages/devtools_app/lib/src/debugger/debugger_screen.dart
+++ b/packages/devtools_app/lib/src/debugger/debugger_screen.dart
@@ -152,7 +152,7 @@ class DebuggerScreenBodyState extends State<DebuggerScreenBody>
               ProgramExplorer(
                 debugController: controller,
                 onSelected: _onLocationSelected,
-              ),
+              )
             ],
           );
         } else {

From 5c7cdfe7390560aa1e1f901099be6b668b225384 Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 09:03:36 -0700
Subject: [PATCH 5/9] Revert "Replace `ScriptPicker` with `ProgramExplorer` on
 `DebuggerScreen` (#3227)" and associated follow-on PRs

---
 .../devtools_app/lib/src/common_widgets.dart  |   4 +-
 .../lib/src/debugger/codeview.dart            |  43 +-
 .../lib/src/debugger/controls.dart            |   6 +-
 .../lib/src/debugger/debugger_controller.dart |  45 +-
 .../lib/src/debugger/debugger_model.dart      |  25 +-
 .../lib/src/debugger/debugger_screen.dart     |  26 +-
 .../lib/src/debugger/program_explorer.dart    | 448 ---------------
 .../debugger/program_explorer_controller.dart | 269 ---------
 .../src/debugger/program_explorer_model.dart  | 509 ------------------
 .../lib/src/debugger/scripts.dart             | 167 ++++++
 .../lib/src/debugger/variables.dart           |   6 +-
 .../devtools_app/lib/src/history_manager.dart |   5 -
 .../lib/src/history_viewport.dart             |  49 +-
 .../lib/src/inspector/diagnostics_node.dart   |  11 +-
 .../lib/src/inspector/inspector_service.dart  |   2 +-
 .../inspector/inspector_tree_controller.dart  |  28 +-
 .../performance/legacy/performance_model.dart |   6 +-
 .../src/performance/performance_model.dart    |   6 +-
 packages/devtools_app/lib/src/theme.dart      |   4 -
 packages/devtools_app/lib/src/tree.dart       |  96 +---
 packages/devtools_app/lib/src/trees.dart      |  41 +-
 .../vm_service_private_extensions.dart        |   4 -
 .../lib/src/vm_service_wrapper.dart           |  20 -
 .../macos/Runner.xcodeproj/project.pbxproj    |   5 +
 .../test/debugger_controller_test.dart        |   6 +-
 .../test/debugger_evalution_test.dart         |   1 -
 .../test/debugger_screen_test.dart            |  38 +-
 .../test/inspector_tree_test.dart             |  10 +-
 packages/devtools_test/lib/mocks.dart         |  30 --
 29 files changed, 323 insertions(+), 1587 deletions(-)
 delete mode 100644 packages/devtools_app/lib/src/debugger/program_explorer.dart
 delete mode 100644 packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
 delete mode 100644 packages/devtools_app/lib/src/debugger/program_explorer_model.dart
 create mode 100644 packages/devtools_app/lib/src/debugger/scripts.dart

diff --git a/packages/devtools_app/lib/src/common_widgets.dart b/packages/devtools_app/lib/src/common_widgets.dart
index 6e33b6db7cb..26c18531102 100644
--- a/packages/devtools_app/lib/src/common_widgets.dart
+++ b/packages/devtools_app/lib/src/common_widgets.dart
@@ -676,7 +676,6 @@ class AreaPaneHeader extends StatelessWidget implements PreferredSizeWidget {
     this.needsLeftBorder = false,
     this.leftActions = const [],
     this.rightActions = const [],
-    this.leftPadding = defaultSpacing,
     this.rightPadding = densePadding,
     this.tall = false,
   }) : super(key: key);
@@ -688,7 +687,6 @@ class AreaPaneHeader extends StatelessWidget implements PreferredSizeWidget {
   final bool needsLeftBorder;
   final List<Widget> leftActions;
   final List<Widget> rightActions;
-  final double leftPadding;
   final double rightPadding;
   final bool tall;
 
@@ -707,7 +705,7 @@ class AreaPaneHeader extends StatelessWidget implements PreferredSizeWidget {
           ),
           color: theme.titleSolidBackgroundColor,
         ),
-        padding: EdgeInsets.only(left: leftPadding, right: rightPadding),
+        padding: EdgeInsets.only(left: defaultSpacing, right: rightPadding),
         alignment: Alignment.centerLeft,
         child: Row(
           children: [
diff --git a/packages/devtools_app/lib/src/debugger/codeview.dart b/packages/devtools_app/lib/src/debugger/codeview.dart
index 411be388f1f..c6f2e8e2294 100644
--- a/packages/devtools_app/lib/src/debugger/codeview.dart
+++ b/packages/devtools_app/lib/src/debugger/codeview.dart
@@ -42,7 +42,6 @@ class CodeView extends StatefulWidget {
   const CodeView({
     Key key,
     this.controller,
-    this.initialPosition,
     this.scriptRef,
     this.parsedScript,
     this.onSelected,
@@ -58,7 +57,6 @@ class CodeView extends StatefulWidget {
   static double get assumedCharacterWidth => scaleByFontFactor(16.0);
 
   final DebuggerController controller;
-  final ScriptLocation initialPosition;
   final ScriptRef scriptRef;
   final ParsedScript parsedScript;
 
@@ -91,15 +89,6 @@ class _CodeViewState extends State<CodeView>
     textController = verticalController.addAndGet();
     horizontalController = ScrollController();
 
-    if (widget.initialPosition != null) {
-      final location = widget.initialPosition.location;
-      // Lines are 1-indexed. Scrolling to line 1 required a scroll position of
-      // 0.
-      final lineIndex = location.line - 1;
-      final scrollPosition = lineIndex * CodeView.rowHeight;
-      verticalController.jumpTo(scrollPosition);
-    }
-
     addAutoDisposeListener(
       widget.controller.scriptLocation,
       _handleScriptLocationChanged,
@@ -135,29 +124,18 @@ class _CodeViewState extends State<CodeView>
   }
 
   void _updateScrollPosition({bool animate = true}) {
-    if (widget.controller.scriptLocation.value?.scriptRef?.uri !=
-        scriptRef?.uri) {
+    if (widget.controller.scriptLocation.value?.scriptRef != scriptRef) {
       return;
     }
 
-    if (!verticalController.hasAttachedControllers) {
-      // TODO(devoncarew): I'm uncertain why this occurs.
-      log('LinkedScrollControllerGroup has no attached controllers');
+    final location = widget.controller.scriptLocation.value?.location;
+    if (location?.line == null) {
       return;
     }
 
-    final location = widget.controller.scriptLocation.value?.location;
-    if (location?.line == null) {
-      // Default to scrolling to the top of the script.
-      if (animate) {
-        verticalController.animateTo(
-          0,
-          duration: longDuration,
-          curve: defaultCurve,
-        );
-      } else {
-        verticalController.jumpTo(0);
-      }
+    if (!verticalController.hasAttachedControllers) {
+      // TODO(devoncarew): I'm uncertain why this occurs.
+      log('LinkedScrollControllerGroup has no attached controllers');
       return;
     }
 
@@ -167,11 +145,10 @@ class _CodeViewState extends State<CodeView>
     // TODO(devoncarew): Adjust this so we don't scroll if we're already in the
     // middle third of the screen.
     if (parsedScript.lineCount * CodeView.rowHeight > extent) {
+      // Scroll to the middle of the screen.
       final lineIndex = location.line - 1;
-      final scrollPosition = lineIndex * CodeView.rowHeight -
-          (widget.controller.shouldCenterScrollLocation
-              ? ((extent - CodeView.rowHeight) / 2)
-              : 0);
+      final scrollPosition =
+          lineIndex * CodeView.rowHeight - (extent - CodeView.rowHeight) / 2;
       if (animate) {
         verticalController.animateTo(
           scrollPosition,
@@ -663,7 +640,7 @@ class _LinesState extends State<Lines> with AutoDisposeMixin {
 
         if (isOutOfViewTop || isOutOfViewBottom) {
           // Scroll this search token to the middle of the view.
-          final targetOffset = math.max<double>(
+          final targetOffset = math.max(
             activeSearch.position.line * CodeView.rowHeight - widget.height / 2,
             0.0,
           );
diff --git a/packages/devtools_app/lib/src/debugger/controls.dart b/packages/devtools_app/lib/src/debugger/controls.dart
index 03012e93d1c..0e35670ec44 100644
--- a/packages/devtools_app/lib/src/debugger/controls.dart
+++ b/packages/devtools_app/lib/src/debugger/controls.dart
@@ -12,6 +12,7 @@ import '../common_widgets.dart';
 import '../theme.dart';
 import '../ui/label.dart';
 import 'debugger_controller.dart';
+import 'scripts.dart';
 
 class DebuggingControls extends StatefulWidget {
   const DebuggingControls({Key key}) : super(key: key);
@@ -117,14 +118,13 @@ class _DebuggingControlsState extends State<DebuggingControls>
 
   Widget _librariesButton() {
     return ValueListenableBuilder(
-      valueListenable: controller.fileExplorerVisible,
+      valueListenable: controller.librariesVisible,
       builder: (context, visible, _) {
-        const libraryIcon = Icons.insert_chart;
         return RoundedOutlinedBorder(
           child: Container(
             color: visible ? Theme.of(context).highlightColor : null,
             child: DebuggerButton(
-              title: 'File Explorer',
+              title: 'Libraries',
               icon: libraryIcon,
               onPressed: controller.toggleLibrariesVisible,
             ),
diff --git a/packages/devtools_app/lib/src/debugger/debugger_controller.dart b/packages/devtools_app/lib/src/debugger/debugger_controller.dart
index 3dd0f156496..8562ad95718 100644
--- a/packages/devtools_app/lib/src/debugger/debugger_controller.dart
+++ b/packages/devtools_app/lib/src/debugger/debugger_controller.dart
@@ -20,7 +20,6 @@ import '../ui/search.dart';
 import '../utils.dart';
 import '../vm_service_wrapper.dart';
 import 'debugger_model.dart';
-import 'program_explorer_controller.dart';
 import 'syntax_highlighter.dart';
 
 // TODO(devoncarew): Add some delayed resume value notifiers (to be used to
@@ -41,7 +40,6 @@ class DebuggerController extends DisposableController
       _showScriptLocation(ScriptLocation(scriptsHistory.current.value));
     };
     scriptsHistory.current.addListener(_scriptHistoryListener);
-    programExplorerController.initialize(currentScriptRef.value);
 
     if (_service != null) {
       initialize();
@@ -122,8 +120,6 @@ class DebuggerController extends DisposableController
   Map<LibraryRef, Future<Set<String>>>
       libraryMemberAndImportsAutocompleteCache = {};
 
-  final programExplorerController = ProgramExplorerController();
-
   final ScriptCache _scriptCache = ScriptCache();
 
   final ScriptsHistory scriptsHistory = ScriptsHistory();
@@ -165,11 +161,8 @@ class DebuggerController extends DisposableController
   final _showFileOpener = ValueNotifier<bool>(false);
 
   /// Jump to the given ScriptRef and optional SourcePosition.
-  void showScriptLocation(
-    ScriptLocation scriptLocation, {
-    bool centerLocation = true,
-  }) {
-    _showScriptLocation(scriptLocation, centerLocation: centerLocation);
+  void showScriptLocation(ScriptLocation scriptLocation) {
+    _showScriptLocation(scriptLocation);
 
     // Update the scripts history (and make sure we don't react to the
     // subsequent event).
@@ -180,11 +173,7 @@ class DebuggerController extends DisposableController
 
   /// Show the given script location (without updating the script navigation
   /// history).
-  void _showScriptLocation(
-    ScriptLocation scriptLocation, {
-    bool centerLocation = true,
-  }) {
-    _shouldCenterScrollLocation = centerLocation;
+  void _showScriptLocation(ScriptLocation scriptLocation) {
     _currentScriptRef.value = scriptLocation?.scriptRef;
 
     _parseCurrentScript();
@@ -193,8 +182,6 @@ class DebuggerController extends DisposableController
     // set to null to ensure that happens.
     _scriptLocation.value = null;
     _scriptLocation.value = scriptLocation;
-
-    programExplorerController.selectScriptNode(scriptLocation.scriptRef);
   }
 
   Future<Script> getScriptForRef(ScriptRef ref) async {
@@ -295,9 +282,6 @@ class DebuggerController extends DisposableController
   /// Return the sorted list of ScriptRefs active in the current isolate.
   ValueListenable<List<ScriptRef>> get sortedScripts => _sortedScripts;
 
-  bool get shouldCenterScrollLocation => _shouldCenterScrollLocation;
-  bool _shouldCenterScrollLocation = true;
-
   final _breakpoints = ValueNotifier<List<Breakpoint>>([]);
 
   ValueListenable<List<Breakpoint>> get breakpoints => _breakpoints;
@@ -320,7 +304,7 @@ class DebuggerController extends DisposableController
 
   final _librariesVisible = ValueNotifier(false);
 
-  ValueListenable<bool> get fileExplorerVisible => _librariesVisible;
+  ValueListenable<bool> get librariesVisible => _librariesVisible;
 
   /// Make the 'Libraries' view on the right-hand side of the screen visible or
   /// hidden.
@@ -624,6 +608,7 @@ class DebuggerController extends DisposableController
 
   void _handleIsolateEvent(Event event) {
     if (event.isolate.id != isolateRef?.id) return;
+
     switch (event.kind) {
       case EventKind.kIsolateReload:
         _updateAfterIsolateReload(event);
@@ -878,12 +863,25 @@ class DebuggerController extends DisposableController
     _populateScriptAndShowLocation(mainScriptRef);
   }
 
+  SourcePosition calculatePosition(Script script, int tokenPos) {
+    final List<List<int>> table = script.tokenPosTable;
+    if (table == null) {
+      return null;
+    }
+
+    return SourcePosition(
+      line: script.getLineNumberFromTokenPos(tokenPos),
+      column: script.getColumnNumberFromTokenPos(tokenPos),
+      tokenPos: tokenPos,
+    );
+  }
+
   Future<BreakpointAndSourcePosition> _createBreakpointWithLocation(
       Breakpoint breakpoint) async {
     if (breakpoint.resolved) {
       final bp = BreakpointAndSourcePosition.create(breakpoint);
       return getScript(bp.scriptRef).then((Script script) {
-        final pos = SourcePosition.calculatePosition(script, bp.tokenPos);
+        final pos = calculatePosition(script, bp.tokenPos);
         return BreakpointAndSourcePosition.create(breakpoint, pos);
       });
     } else {
@@ -900,8 +898,7 @@ class DebuggerController extends DisposableController
     }
 
     final script = await getScript(location.script);
-    final position =
-        SourcePosition.calculatePosition(script, location.tokenPos);
+    final position = calculatePosition(script, location.tokenPos);
     return StackFrameAndSourcePosition(frame, position: position);
   }
 
@@ -1006,7 +1003,7 @@ class DebuggerController extends DisposableController
     for (SourceReportRange range in report.ranges) {
       if (range.possibleBreakpoints != null) {
         for (int tokenPos in range.possibleBreakpoints) {
-          positions.add(SourcePosition.calculatePosition(script, tokenPos));
+          positions.add(calculatePosition(script, tokenPos));
         }
       }
     }
diff --git a/packages/devtools_app/lib/src/debugger/debugger_model.dart b/packages/devtools_app/lib/src/debugger/debugger_model.dart
index 9a45daa5cb7..aa200babd9e 100644
--- a/packages/devtools_app/lib/src/debugger/debugger_model.dart
+++ b/packages/devtools_app/lib/src/debugger/debugger_model.dart
@@ -94,27 +94,10 @@ class ScriptLocation {
   String toString() => '${scriptRef.uri} $location';
 }
 
+/// A line, column, and an optional tokenPos.
 class SourcePosition {
-  const SourcePosition({
-    @required this.line,
-    @required this.column,
-    this.file,
-    this.tokenPos,
-  });
-
-  factory SourcePosition.calculatePosition(Script script, int tokenPos) {
-    if (script.tokenPosTable == null) {
-      return null;
-    }
-
-    return SourcePosition(
-      line: script.getLineNumberFromTokenPos(tokenPos),
-      column: script.getColumnNumberFromTokenPos(tokenPos),
-      tokenPos: tokenPos,
-    );
-  }
+  SourcePosition({@required this.line, @required this.column, this.tokenPos});
 
-  final String file;
   final int line;
   final int column;
   final int tokenPos;
@@ -530,9 +513,7 @@ List<Variable> _createVariablesForAssociations(
       isolateRef: isolateRef,
     );
     variables.add(
-      Variable.text('[Entry $i]')
-        ..addChild(key)
-        ..addChild(value),
+      Variable.text('[Entry $i]')..addChild(key)..addChild(value),
     );
   }
   return variables;
diff --git a/packages/devtools_app/lib/src/debugger/debugger_screen.dart b/packages/devtools_app/lib/src/debugger/debugger_screen.dart
index d8f4f08a6f0..155cf81941c 100644
--- a/packages/devtools_app/lib/src/debugger/debugger_screen.dart
+++ b/packages/devtools_app/lib/src/debugger/debugger_screen.dart
@@ -26,7 +26,7 @@ import 'controls.dart';
 import 'debugger_controller.dart';
 import 'debugger_model.dart';
 import 'key_sets.dart';
-import 'program_explorer.dart';
+import 'scripts.dart';
 import 'variables.dart';
 
 class DebuggerScreen extends Screen {
@@ -102,10 +102,7 @@ class DebuggerScreenBodyState extends State<DebuggerScreenBody>
 
   void _onLocationSelected(ScriptLocation location) {
     if (location != null) {
-      controller.showScriptLocation(
-        location,
-        centerLocation: location.location == null,
-      );
+      controller.showScriptLocation(location);
     }
   }
 
@@ -140,7 +137,7 @@ class DebuggerScreenBodyState extends State<DebuggerScreenBody>
     );
 
     final codeArea = ValueListenableBuilder(
-      valueListenable: controller.fileExplorerVisible,
+      valueListenable: controller.librariesVisible,
       builder: (context, visible, _) {
         if (visible) {
           // TODO(devoncarew): Animate this opening and closing.
@@ -149,10 +146,17 @@ class DebuggerScreenBodyState extends State<DebuggerScreenBody>
             initialFractions: const [0.70, 0.30],
             children: [
               codeView,
-              ProgramExplorer(
-                debugController: controller,
-                onSelected: _onLocationSelected,
-              )
+              ValueListenableBuilder(
+                valueListenable: controller.sortedScripts,
+                builder: (context, scripts, _) {
+                  return ScriptPicker(
+                    key: DebuggerScreenBody.scriptViewKey,
+                    controller: controller,
+                    scripts: scripts,
+                    onSelected: _onLocationSelected,
+                  );
+                },
+              ),
             ],
           );
         } else {
@@ -389,7 +393,7 @@ class _DebuggerStatusState extends State<DebuggerStatus> with AutoDisposeMixin {
     final fileName = ' at ' + frame.location.script.uri.split('/').last;
     final script = await widget.controller.getScript(frame.location.script);
     final pos =
-        SourcePosition.calculatePosition(script, frame.location.tokenPos);
+        widget.controller.calculatePosition(script, frame.location.tokenPos);
 
     return 'paused$reason$fileName $pos';
   }
diff --git a/packages/devtools_app/lib/src/debugger/program_explorer.dart b/packages/devtools_app/lib/src/debugger/program_explorer.dart
deleted file mode 100644
index b11e49f13f2..00000000000
--- a/packages/devtools_app/lib/src/debugger/program_explorer.dart
+++ /dev/null
@@ -1,448 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'package:flutter/material.dart';
-import 'package:vm_service/vm_service.dart' hide Stack;
-
-import '../common_widgets.dart';
-import '../flex_split_column.dart';
-import '../theme.dart';
-import '../tree.dart';
-import '../utils.dart';
-import 'debugger_controller.dart';
-import 'debugger_model.dart';
-import 'program_explorer_controller.dart';
-import 'program_explorer_model.dart';
-
-const containerIcon = Icons.folder;
-const libraryIcon = Icons.insert_drive_file;
-const listItemHeight = 40.0;
-
-double get _programExplorerRowHeight => scaleByFontFactor(22.0);
-
-class _ProgramExplorerRow extends StatelessWidget {
-  const _ProgramExplorerRow({
-    @required this.controller,
-    @required this.node,
-    this.onTap,
-  });
-
-  final ProgramExplorerController controller;
-  final VMServiceObjectNode node;
-  final VoidCallback onTap;
-
-  @override
-  Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-
-    String text = node.name;
-    final toolTip = _tooltipForNode();
-
-    if (node.object is ClassRef ||
-        node.object is Func ||
-        node.object is Field) {
-      text = toolTip;
-    }
-
-    return DevToolsTooltip(
-      tooltip: toolTip ?? node.name,
-      textStyle: theme.toolTipFixedFontStyle,
-      child: InkWell(
-        onTap: onTap,
-        child: Row(
-          children: [
-            ProgramStructureIcon(
-              object: node.object,
-            ),
-            const SizedBox(width: densePadding),
-            Flexible(
-              child: Text(
-                text,
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
-                style: theme.fixedFontStyle,
-              ),
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-
-  String _tooltipForNode() {
-    String toolTip;
-    if (node.object is ClassRef) {
-      final clazz = node.object as ClassRef;
-      toolTip = '${clazz.name}';
-      if (clazz.typeParameters != null) {
-        toolTip +=
-            '<' + clazz.typeParameters.map((e) => e.name).join(', ') + '>';
-      }
-    } else if (node.object is Func) {
-      final func = node.object as Func;
-      final isInstanceMethod = func.owner is ClassRef;
-      final subtext = _buildFunctionTypeText(
-        func.name,
-        func.signature,
-        isInstanceMethod: isInstanceMethod,
-      );
-      toolTip = '${func.name}$subtext';
-    } else if (node.object is Field) {
-      final field = node.object as Field;
-      final subtext = _buildFieldTypeText(field);
-      toolTip = '$subtext ${field.name}';
-    } else if (node.script != null) {
-      toolTip = node.script.uri;
-    }
-    return toolTip;
-  }
-
-  /// Builds a string representation of a field declaration.
-  ///
-  /// Examples:
-  ///   - final String
-  ///   - static const int
-  ///   - List<X0>
-  String _buildFieldTypeText(Field field) {
-    final buffer = StringBuffer();
-    if (field.isStatic) {
-      buffer.write('static ');
-    }
-    if (field.isConst) {
-      buffer.write('const ');
-    }
-    if (field.isFinal && !field.isConst) {
-      buffer.write('final ');
-    }
-    buffer.write(field.declaredType.name);
-    return buffer.toString();
-  }
-
-  /// Builds a string representation of a function signature
-  ///
-  /// Examples:
-  ///   - Foo<T>(T) -> dynamic
-  ///   - Bar(String, int) -> void
-  ///   - Baz(String, [int]) -> void
-  ///   - Faz(String, {String? bar, required int baz}) -> int
-  String _buildFunctionTypeText(
-    String functionName,
-    InstanceRef signature, {
-    bool isInstanceMethod = false,
-  }) {
-    final buffer = StringBuffer();
-    if (signature.typeParameters != null) {
-      final typeParams = signature.typeParameters;
-      buffer.write('<');
-      for (int i = 0; i < typeParams.length; ++i) {
-        buffer.write(typeParams[i].name);
-        if (i + 1 != typeParams.length) {
-          buffer.write(', ');
-        }
-      }
-      buffer.write('>');
-    }
-    buffer.write('(');
-    String closingTag;
-    for (int i = isInstanceMethod ? 1 : 0;
-        i < signature.parameters.length;
-        ++i) {
-      final param = signature.parameters[i];
-      if (!param.fixed && closingTag == null) {
-        if (param.name == null) {
-          closingTag = ']';
-          buffer.write('[');
-        } else {
-          closingTag = '}';
-          buffer.write('{');
-        }
-      }
-      if (param.required != null && param.required) {
-        buffer.write('required ');
-      }
-      if (param.parameterType.name == null) {
-        buffer.write(_buildFunctionTypeText('Function', param.parameterType));
-      } else {
-        buffer.write(param.parameterType.name);
-      }
-      if (param.name != null) {
-        buffer.write(' ${param.name}');
-      }
-      if (i + 1 != signature.parameters.length) {
-        buffer.write(', ');
-      } else if (closingTag != null) {
-        buffer.write(closingTag);
-      }
-    }
-    buffer.write(') → ');
-    if (signature.returnType.name == null) {
-      buffer.write(_buildFunctionTypeText('Function', signature.returnType));
-    } else {
-      buffer.write(signature.returnType.name);
-    }
-
-    return buffer.toString();
-  }
-}
-
-class ProgramStructureIcon extends StatelessWidget {
-  const ProgramStructureIcon({
-    @required this.object,
-  });
-
-  final ObjRef object;
-
-  @override
-  Widget build(BuildContext context) {
-    final theme = Theme.of(context);
-    final colorScheme = theme.colorScheme;
-    IconData icon;
-    String character;
-    Color color = colorScheme.functionSyntaxColor;
-    bool isShortCharacter;
-    if (object is ClassRef) {
-      character = 'c';
-      isShortCharacter = true;
-      color = colorScheme.declarationsSyntaxColor;
-    } else if (object is FuncRef) {
-      character = 'm';
-      isShortCharacter = true;
-      color = colorScheme.functionSyntaxColor;
-    } else if (object is FieldRef) {
-      character = 'f';
-      isShortCharacter = false;
-      color = colorScheme.variableSyntaxColor;
-    } else if (object is LibraryRef) {
-      icon = Icons.book;
-      color = colorScheme.modifierSyntaxColor;
-    } else if (object is ScriptRef) {
-      icon = libraryIcon;
-      color = colorScheme.stringSyntaxColor;
-    } else {
-      icon = containerIcon;
-    }
-
-    assert((icon == null && character != null && isShortCharacter != null) ||
-        (icon != null && character == null && isShortCharacter == null));
-
-    return SizedBox(
-      height: defaultIconSize,
-      width: defaultIconSize,
-      child: Container(
-        decoration: icon == null
-            ? BoxDecoration(
-                color: color,
-                shape: BoxShape.circle,
-              )
-            : null,
-        child: icon == null
-            ? Center(
-                child: Text(
-                  character,
-                  style: TextStyle(
-                    height: 1,
-                    fontFamily: theme.fixedFontStyle.fontFamily,
-                    color: theme.colorScheme.defaultBackgroundColor,
-                    fontSize: chartFontSizeSmall,
-                  ),
-                  // Required to center the individual character within the
-                  // shape. Since letters like 'm' are shorter than letters
-                  // like 'f', there's padding applied to the top of shorter
-                  // characters in order for everything to align properly.
-                  // Since we're only dealing with individual characters, we
-                  // want to disable this behavior so shorter characters don't
-                  // appear to be slightly below center.
-                  textHeightBehavior: TextHeightBehavior(
-                    applyHeightToFirstAscent: isShortCharacter,
-                    applyHeightToLastDescent: false,
-                  ),
-                ),
-              )
-            : Icon(
-                icon,
-                size: defaultIconSize,
-                color: color,
-              ),
-      ),
-    );
-  }
-}
-
-class _FileExplorer extends StatelessWidget {
-  const _FileExplorer({
-    @required this.controller,
-    @required this.onItemSelected,
-    @required this.onItemExpanded,
-  });
-
-  final ProgramExplorerController controller;
-  final Function(VMServiceObjectNode) onItemSelected;
-  final Function(VMServiceObjectNode) onItemExpanded;
-
-  @override
-  Widget build(BuildContext context) {
-    return ValueListenableBuilder<List<VMServiceObjectNode>>(
-      valueListenable: controller.rootObjectNodes,
-      builder: (context, nodes, _) {
-        return TreeView<VMServiceObjectNode>(
-          itemExtent: _programExplorerRowHeight,
-          dataRoots: nodes,
-          onItemSelected: onItemSelected,
-          onItemExpanded: onItemExpanded,
-          dataDisplayProvider: (node, onTap) {
-            return _ProgramExplorerRow(
-              controller: controller,
-              node: node,
-              onTap: () {
-                controller.selectNode(node);
-                onTap();
-              },
-            );
-          },
-        );
-      },
-    );
-  }
-}
-
-class _ProgramOutlineView extends StatelessWidget {
-  const _ProgramOutlineView({
-    @required this.controller,
-    @required this.onItemSelected,
-    @required this.onItemExpanded,
-  });
-
-  final ProgramExplorerController controller;
-  final Function(VMServiceObjectNode) onItemSelected;
-  final Function(VMServiceObjectNode) onItemExpanded;
-
-  @override
-  Widget build(BuildContext context) {
-    return ValueListenableBuilder<List<VMServiceObjectNode>>(
-      valueListenable: controller.outlineNodes,
-      builder: (context, nodes, _) {
-        if (nodes == null || nodes.isEmpty) {
-          return const Center(
-            child: Text('Nothing to inspect'),
-          );
-        }
-        return TreeView<VMServiceObjectNode>(
-          itemExtent: _programExplorerRowHeight,
-          dataRoots: nodes,
-          onItemSelected: onItemSelected,
-          onItemExpanded: onItemExpanded,
-          dataDisplayProvider: (node, onTap) {
-            return _ProgramExplorerRow(
-              controller: controller,
-              node: node,
-              onTap: onTap,
-            );
-          },
-        );
-      },
-    );
-  }
-}
-
-/// Picker that displays the program's structure, allowing for navigation and
-/// filtering.
-class ProgramExplorer extends StatelessWidget {
-  ProgramExplorer({
-    Key key,
-    @required this.debugController,
-    @required this.onSelected,
-  })  : controller = debugController.programExplorerController,
-        super(key: key);
-
-  final ProgramExplorerController controller;
-  final DebuggerController debugController;
-  final void Function(ScriptLocation) onSelected;
-
-  @override
-  Widget build(BuildContext context) {
-    return ValueListenableBuilder<bool>(
-      valueListenable: controller.initialized,
-      builder: (context, initialized, _) {
-        Widget body;
-        if (!initialized) {
-          body = const CenteredCircularProgressIndicator();
-        } else {
-          body = LayoutBuilder(
-            builder: (context, constraints) {
-              return FlexSplitColumn(
-                totalHeight: constraints.maxHeight,
-                initialFractions: const [0.7, 0.3],
-                minSizes: const [0.0, 0.0],
-                headers: const <PreferredSizeWidget>[
-                  AreaPaneHeader(
-                    title: Text('File Explorer'),
-                    needsTopBorder: false,
-                  ),
-                  AreaPaneHeader(title: Text('Outline')),
-                ],
-                children: [
-                  _FileExplorer(
-                    controller: controller,
-                    onItemExpanded: onItemExpanded,
-                    onItemSelected: onItemSelected,
-                  ),
-                  _ProgramOutlineView(
-                    controller: controller,
-                    onItemExpanded: onItemExpanded,
-                    onItemSelected: onItemSelected,
-                  ),
-                ],
-              );
-            },
-          );
-        }
-        return OutlineDecoration(
-          child: body,
-        );
-      },
-    );
-  }
-
-  void onItemSelected(VMServiceObjectNode node) async {
-    if (!node.isSelectable) {
-      node.toggleExpansion();
-      return;
-    }
-
-    if (node.object != null && node.object is! Obj) {
-      await controller.populateNode(node);
-    }
-
-    // If the node is collapsed and we select it, we'll always want to expand
-    // to display the children.
-    if (!node.isExpanded) {
-      node.expand();
-    }
-
-    ScriptRef script = node.script;
-    int tokenPos = 0;
-    if (node.object != null &&
-        (node.object is FieldRef ||
-            node.object is FuncRef ||
-            node.object is ClassRef)) {
-      final location = (node.object as dynamic).location;
-      tokenPos = location.tokenPos;
-      script = location.script;
-    }
-
-    script = await debugController.getScript(script);
-    final location = tokenPos == 0
-        ? null
-        : SourcePosition.calculatePosition(script, tokenPos);
-    onSelected(
-      ScriptLocation(script, location: location),
-    );
-  }
-
-  void onItemExpanded(VMServiceObjectNode node) async {
-    if (node.object != null && node.object is! Obj) {
-      await controller.populateNode(node);
-    }
-  }
-}
diff --git a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart b/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
deleted file mode 100644
index 79c43bdf82b..00000000000
--- a/packages/devtools_app/lib/src/debugger/program_explorer_controller.dart
+++ /dev/null
@@ -1,269 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:async';
-
-import 'package:flutter/foundation.dart';
-import 'package:vm_service/vm_service.dart';
-
-import '../auto_dispose.dart';
-import '../globals.dart';
-import '../utils.dart';
-import 'program_explorer_model.dart';
-
-class ProgramExplorerController extends DisposableController
-    with AutoDisposeControllerMixin {
-  ProgramExplorerController() {
-    addAutoDisposeListener(
-      serviceManager.isolateManager.selectedIsolate,
-      refresh,
-    );
-  }
-
-  /// A list of objects containing the contents of each library.
-  final _programStructure = <VMServiceLibraryContents>[];
-
-  /// The outline view nodes for the currently selected library.
-  ValueListenable<List<VMServiceObjectNode>> get outlineNodes => _outlineNodes;
-  final _outlineNodes = ListValueNotifier<VMServiceObjectNode>([]);
-
-  /// The currently selected node.
-  VMServiceObjectNode _selected;
-
-  /// The processed roots of the tree.
-  ValueListenable<List<VMServiceObjectNode>> get rootObjectNodes =>
-      _rootObjectNodes;
-  final _rootObjectNodes = ListValueNotifier<VMServiceObjectNode>([]);
-
-  /// Cache of object IDs to their containing library to allow for easier
-  /// refreshing of library content, particularly for scripts.
-  final _objectIdToLibrary = <String, LibraryRef>{};
-
-  IsolateRef _isolate;
-
-  /// Notifies that the controller has finished initializing.
-  ValueListenable<bool> get initialized => _initialized;
-  final _initialized = ValueNotifier<bool>(false);
-  bool _initializing = false;
-
-  /// Returns true if [function] is a getter or setter that was not explicitly
-  /// defined (e.g., `int foo` creates `int get foo` and `set foo(int)`).
-  static bool _isSyntheticAccessor(FuncRef function, List<FieldRef> fields) {
-    for (final field in fields) {
-      if (function.name == field.name || function.name == '${field.name}=') {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  /// Initializes the program structure.
-  // TODO(bkonyi): reinitialize after hot reload.
-  Future<void> initialize([ScriptRef initialScript]) async {
-    if (_initializing) {
-      return;
-    }
-    _initializing = true;
-    _isolate = serviceManager.isolateManager.selectedIsolate.value;
-    final libraries = _isolate != null
-        ? await Future.wait(
-            serviceManager.isolateManager
-                .isolateDebuggerState(_isolate)
-                .isolateNow
-                .libraries
-                .map(
-                  (lib) => VMServiceLibraryContents.getLibraryContents(lib),
-                ),
-          )
-        : <VMServiceLibraryContents>[];
-
-    void mapIdsToLibrary(LibraryRef lib, Iterable<ObjRef> objs) {
-      for (final e in objs) {
-        _objectIdToLibrary[e.id] = lib;
-      }
-    }
-
-    for (final libContents in libraries) {
-      final lib = libContents.lib;
-      mapIdsToLibrary(lib, [lib]);
-      mapIdsToLibrary(lib, lib.scripts);
-      mapIdsToLibrary(lib, libContents.classes);
-      mapIdsToLibrary(lib, libContents.fields);
-
-      // Filter out synthetic getters/setters
-      final filteredFunctions = libContents.functions
-          .where(
-            (e) => !_isSyntheticAccessor(e, libContents.fields),
-          )
-          .toList();
-      libContents.functions.clear();
-      libContents.functions.addAll(filteredFunctions);
-      mapIdsToLibrary(lib, libContents.functions);
-
-      // Account for entries in library parts.
-      mapIdsToLibrary(lib, libContents.functions.map((e) => e.location.script));
-      mapIdsToLibrary(lib, libContents.classes.map((e) => e.location.script));
-      mapIdsToLibrary(lib, libContents.fields.map((e) => e.location.script));
-    }
-
-    _programStructure.addAll(libraries);
-
-    // Build the initial tree.
-    final nodes = VMServiceObjectNode.createRootsFrom(
-      this,
-      _programStructure,
-    );
-    if (initialScript != null) {
-      _selectScriptNode(initialScript, nodes);
-    }
-    _rootObjectNodes.addAll(nodes);
-    _initialized.value = true;
-  }
-
-  void selectScriptNode(ScriptRef script) {
-    if (!initialized.value) {
-      return;
-    }
-    _selectScriptNode(script, _rootObjectNodes.value);
-    _rootObjectNodes.notifyListeners();
-  }
-
-  void _selectScriptNode(
-    ScriptRef script,
-    List<VMServiceObjectNode> nodes,
-  ) {
-    for (final node in nodes) {
-      final result = node.firstChildWithCondition(
-        (node) => node.script?.uri == script.uri,
-      );
-      if (result != null) {
-        selectNode(result);
-        result.expandAscending();
-        return;
-      }
-    }
-  }
-
-  /// Clears controller state and re-initializes.
-  Future<void> refresh() async {
-    _objectIdToLibrary.clear();
-    _selected = null;
-    _outlineNodes.clear();
-    _initialized.value = false;
-    _initializing = false;
-    _programStructure.clear();
-    return await initialize();
-  }
-
-  /// Marks [node] as the currently selected node, clearing the selection state
-  /// of any currently selected node.
-  void selectNode(VMServiceObjectNode node) async {
-    if (!node.isSelectable) {
-      return;
-    }
-    if (_selected != node) {
-      node.select();
-      _selected?.unselect();
-      _selected = node;
-      _outlineNodes
-        ..clear()
-        ..addAll(await _selected.outline);
-    }
-  }
-
-  /// Updates `node` with a fully populated VM service [Obj].
-  ///
-  /// If `node.object` is already an instance of [Obj], this function
-  /// immediately returns.
-  Future<void> populateNode(VMServiceObjectNode node) async {
-    final object = node.object;
-    if (object == null || object is Obj) {
-      return;
-    }
-    final id = node.object.id;
-    final service = serviceManager.service;
-
-    // We don't know if the object ID is still valid. Re-request the library
-    // and find the object again.
-    final lib = _objectIdToLibrary[id];
-
-    final refreshedLib =
-        await service.getObject(_isolate.id, lib.id) as Library;
-    dynamic updatedObj;
-
-    // Find the relevant object reference in the refreshed library.
-    if (object is ClassRef) {
-      updatedObj = refreshedLib.classes.firstWhere(
-        (k) => k.name == object.name,
-      );
-    } else if (object is FieldRef) {
-      updatedObj = refreshedLib.variables.firstWhere(
-        (v) => v.name == object.name,
-      );
-    } else if (object is FuncRef) {
-      updatedObj = refreshedLib.functions.firstWhere(
-        (f) => f.name == object.name,
-      );
-    } else if (object is ScriptRef) {
-      updatedObj = refreshedLib.scripts.firstWhere(
-        (s) => s.uri == object.uri,
-      );
-    } else {
-      throw StateError('Unexpected type: ${object.runtimeType}');
-    }
-
-    // Request the full object for the node we're interested in and update all
-    // instances of the original reference object in the program structure with
-    // the full object.
-    updatedObj = await service.getObject(_isolate.id, updatedObj.id);
-
-    final library = _programStructure.firstWhere(
-      (e) => e.lib.uri == lib.uri,
-    );
-    if (updatedObj is Class) {
-      final clazz = updatedObj;
-      final i = library.classes.indexWhere(
-        (c) => c.name == clazz.name,
-      );
-      library.classes[i] = clazz;
-      final fields = await Future.wait(
-        clazz.fields.map(
-          (e) => service.getObject(_isolate.id, e.id),
-        ),
-      );
-      clazz.fields
-        ..clear()
-        ..addAll(fields.cast<FieldRef>());
-
-      final functions = await Future.wait(
-        clazz.functions.map(
-          (e) => service.getObject(_isolate.id, e.id).then((e) => e as Func),
-        ),
-      );
-      clazz.functions
-        ..clear()
-        ..addAll(
-          functions
-              .where((e) => !_isSyntheticAccessor(e, clazz.fields))
-              .cast<FuncRef>(),
-        );
-    } else if (updatedObj is Field) {
-      final i = library.fields.indexWhere(
-        (f) => f.name == updatedObj.name,
-      );
-      library.fields[i] = updatedObj;
-    } else if (object is Func) {
-      final i = library.functions.indexWhere(
-        (f) => f.name == updatedObj.name,
-      );
-      library.functions[i] = updatedObj;
-    }
-
-    _objectIdToLibrary.remove(id);
-    _objectIdToLibrary[updatedObj.id] = library.lib;
-
-    // Sets the contents of the node to contain the full object.
-    node.updateObject(updatedObj);
-  }
-}
diff --git a/packages/devtools_app/lib/src/debugger/program_explorer_model.dart b/packages/devtools_app/lib/src/debugger/program_explorer_model.dart
deleted file mode 100644
index be6fa9025f2..00000000000
--- a/packages/devtools_app/lib/src/debugger/program_explorer_model.dart
+++ /dev/null
@@ -1,509 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'package:vm_service/vm_service.dart';
-
-import '../globals.dart';
-import '../trees.dart';
-import '../version.dart';
-import 'program_explorer_controller.dart';
-
-class VMServiceLibraryContents {
-  const VMServiceLibraryContents({
-    this.lib,
-    this.classes,
-    this.functions,
-    this.fields,
-  });
-
-  final Library lib;
-  final List<ClassRef> classes;
-  final List<FuncRef> functions;
-  final List<FieldRef> fields;
-
-  static Future<VMServiceLibraryContents> getLibraryContents(
-    LibraryRef libRef,
-  ) async {
-    final isolateId = serviceManager.isolateManager.selectedIsolate.value.id;
-    final service = serviceManager.service;
-
-    final lib = await service.getObject(isolateId, libRef.id) as Library;
-    var classes = <ClassRef>[];
-    var functions = <FuncRef>[];
-    var fields = <FieldRef>[];
-
-    classes.addAll(lib.classes);
-    functions.addAll(lib.functions);
-    fields.addAll(lib.variables);
-
-    // Before 3.46, ClassRef, FuncRef, and FieldRef didn't contain location
-    // information and couldn't be mapped to their parent scripts. For older
-    // versions of the protocol, we need to request the full objects for
-    // everything. We'll avoid doing this for versions >= 3.46 and lazily
-    // populate the tree with full instances as the user navigates.
-    if (!await service.isProtocolVersionSupported(
-      supportedVersion: SemanticVersion(major: 3, minor: 46),
-    )) {
-      final classesRequests = lib.classes.map(
-        (clazz) async => await service.getObject(isolateId, clazz.id) as Class,
-      );
-
-      classes = await Future.wait(classesRequests);
-    }
-
-    final funcsRequests = lib.functions.map(
-      (func) async => await service.getObject(isolateId, func.id) as Func,
-    );
-    functions = await Future.wait(funcsRequests);
-
-    final fieldsRequests = lib.variables.map(
-      (field) async => await service.getObject(isolateId, field.id) as Field,
-    );
-    fields = await Future.wait(fieldsRequests);
-
-    // Remove scripts pulled into libraries via mixins.
-    lib.scripts.removeWhere((e) => !e.uri.contains(lib.uri));
-
-    return VMServiceLibraryContents(
-      lib: lib,
-      classes: classes,
-      functions: functions,
-      fields: fields,
-    );
-  }
-}
-
-/// A node in a tree of VM service objects.
-///
-/// A node can represent one of the following:
-///   - Directory
-///   - Library (with or without a script)
-///   - Script
-///   - Class
-///   - Field
-///   - Function
-class VMServiceObjectNode extends TreeNode<VMServiceObjectNode> {
-  VMServiceObjectNode(
-    this.controller,
-    this.name,
-    this.object, {
-    this.isSelectable = true,
-  });
-
-  static const dartPrefix = 'dart:';
-  static const packagePrefix = 'package:';
-
-  final ProgramExplorerController controller;
-  final String name;
-  bool isSelectable;
-
-  ObjRef object;
-  ScriptRef script;
-
-  /// This exists to allow for O(1) lookup of children when building the tree.
-  final _childrenAsMap = <String, VMServiceObjectNode>{};
-
-  @override
-  bool shouldShow() {
-    return true;
-  }
-
-  // TODO(bkonyi): handle empty classes
-  @override
-  bool get isExpandable => super.isExpandable || object is ClassRef;
-
-  bool get isDirectory => script == null && object == null;
-
-  List<VMServiceObjectNode> _outline;
-  Future<List<VMServiceObjectNode>> get outline async {
-    if (_outline != null) {
-      return _outline;
-    }
-    final root = VMServiceObjectNode(
-      controller,
-      '<root>',
-      ObjRef(id: '0'),
-    );
-
-    String uri;
-    Library lib;
-    if (object is Library) {
-      lib = object as Library;
-      uri = lib.uri;
-    } else {
-      // Try to find the library in the tree. If the current node isn't a
-      // library node, it's likely one of its parents are.
-      VMServiceObjectNode libNode = this;
-      while (libNode != null && libNode.object is! Library) {
-        libNode = libNode.parent;
-      }
-
-      // In the case of patch files, the parent nodes won't include a library.
-      // We'll need to search for the library URI that is a prefix of the
-      // script's URI.
-      if (libNode == null) {
-        final service = serviceManager.service;
-        final isolate = serviceManager.isolateManager.selectedIsolate.value;
-        final libRef = serviceManager.isolateManager
-            .isolateDebuggerState(isolate)
-            .isolateNow
-            .libraries
-            .firstWhere(
-              (lib) => script.uri.startsWith(lib.uri),
-            );
-        lib = await service.getObject(isolate.id, libRef.id);
-      } else {
-        lib = libNode.object as Library;
-      }
-      final ScriptRef s = (object is ScriptRef) ? object : script;
-      uri = s.uri;
-    }
-
-    for (final clazz in lib.classes) {
-      if (clazz.location.script.uri == uri) {
-        final clazzNode = VMServiceObjectNode(
-          controller,
-          clazz.name,
-          clazz,
-        );
-        if (clazz is Class) {
-          for (final function in clazz.functions) {
-            clazzNode._lookupOrCreateChild(function.name, function);
-          }
-          for (final field in clazz.fields) {
-            clazzNode._lookupOrCreateChild(field.name, field);
-          }
-        }
-        root.addChild(clazzNode);
-      }
-    }
-
-    for (final function in lib.functions) {
-      if (function.location.script.uri == uri) {
-        final node = VMServiceObjectNode(
-          controller,
-          function.name,
-          function,
-        );
-        await controller.populateNode(node);
-        root.addChild(
-          node,
-        );
-      }
-    }
-
-    for (final field in lib.variables) {
-      if (field.location.script.uri == uri) {
-        final node = VMServiceObjectNode(
-          controller,
-          field.name,
-          field,
-        );
-        await controller.populateNode(node);
-        root.addChild(
-          VMServiceObjectNode(
-            controller,
-            field.name,
-            field,
-          ),
-        );
-      }
-    }
-
-    // Clear out the _childrenAsMap map.
-    root._trimChildrenAsMapEntries();
-
-    root._sortEntriesByType();
-    _outline = root.children;
-    return _outline;
-  }
-
-  /// Given a flat list of service protocol scripts, return a tree of scripts
-  /// representing the best hierarchical grouping.
-  static List<VMServiceObjectNode> createRootsFrom(
-    ProgramExplorerController controller,
-    List<VMServiceLibraryContents> libs,
-  ) {
-    // The name of this node is not exposed to users.
-    final root = VMServiceObjectNode(controller, '<root>', ObjRef(id: '0'));
-
-    for (var lib in libs) {
-      for (final script in lib.lib.scripts) {
-        _buildScriptNode(root, script, lib: lib.lib);
-      }
-    }
-
-    // Clear out the _childrenAsMap map.
-    root._trimChildrenAsMapEntries();
-
-    final processed = root.children
-        .map((e) => e._collapseSingleChildDirectoryNodes())
-        .toList();
-    root.children.clear();
-    root.addAllChildren(processed);
-
-    // Sort each subtree to use the following ordering:
-    //   - Scripts
-    //   - Classes
-    //   - Functions
-    //   - Variables
-    root._sortEntriesByType();
-
-    // Place the root library's parent node at the top of the explorer if it's
-    // part of a package. Otherwise, it's a file path and its directory should
-    // appear near the top of the list anyway.
-    final rootLib =
-        serviceManager.isolateManager.selectedIsolateState.isolateNow.rootLib;
-    if (rootLib.uri.startsWith('package:') ||
-        rootLib.uri.startsWith('google3:')) {
-      final parts = rootLib.uri.split('/')..removeLast();
-      final path = parts.join('/');
-      for (int i = 0; i < root.children.length; ++i) {
-        if (root.children[i].name.startsWith(path)) {
-          final rootLibNode = root.removeChildAtIndex(i);
-          root.addChild(rootLibNode, index: 0);
-          break;
-        }
-      }
-    }
-
-    return root.children;
-  }
-
-  static VMServiceObjectNode _buildScriptNode(
-    VMServiceObjectNode node,
-    ScriptRef script, {
-    LibraryRef lib,
-  }) {
-    final parts = script.uri.split('/');
-    final name = parts.removeLast();
-
-    for (final part in parts) {
-      // Directory nodes shouldn't be selectable unless they're a library node.
-      node = node._lookupOrCreateChild(
-        part,
-        null,
-        isSelectable: false,
-      );
-    }
-
-    node = node._lookupOrCreateChild(name, script);
-    if (!node.isSelectable) {
-      node.isSelectable = true;
-    }
-    node.script = script;
-
-    // If this is a top-level node and a library is specified, this must be a
-    // library node.
-    if (parts.isEmpty && lib != null) {
-      node.object = lib;
-    }
-    return node;
-  }
-
-  VMServiceObjectNode _lookupOrCreateChild(
-    String name,
-    ObjRef object, {
-    bool isSelectable = true,
-  }) {
-    return _childrenAsMap.putIfAbsent(
-      name,
-      () => _createChild(name, object, isSelectable: isSelectable),
-    );
-  }
-
-  VMServiceObjectNode _createChild(
-    String name,
-    ObjRef object, {
-    bool isSelectable = true,
-  }) {
-    final child = VMServiceObjectNode(
-      controller,
-      name,
-      object,
-      isSelectable: isSelectable,
-    );
-    addChild(child);
-    return child;
-  }
-
-  VMServiceObjectNode _collapseSingleChildDirectoryNodes() {
-    if (children.length == 1) {
-      final child = children.first;
-      if (child.isDirectory) {
-        final collapsed = VMServiceObjectNode(
-          controller,
-          '$name/${child.name}',
-          null,
-          isSelectable: false,
-        );
-        collapsed.addAllChildren(child.children);
-        return collapsed._collapseSingleChildDirectoryNodes();
-      }
-      return this;
-    }
-    final updated = children
-        .map(
-          (e) => e._collapseSingleChildDirectoryNodes(),
-        )
-        .toList();
-    children.clear();
-    addAllChildren(updated);
-    return this;
-  }
-
-  void updateObject(Obj object) {
-    if (this.object is! Class && object is Class) {
-      for (final function in object.functions) {
-        _createChild(function.name, function);
-      }
-      for (final field in object.fields) {
-        _createChild(field.name, field);
-      }
-      _sortEntriesByType();
-    }
-    this.object = object;
-  }
-
-  /// Clear the _childrenAsMap map recursively to save memory.
-  void _trimChildrenAsMapEntries() {
-    _childrenAsMap.clear();
-
-    for (var child in children) {
-      child._trimChildrenAsMapEntries();
-    }
-  }
-
-  void _sortEntriesByType() {
-    final userDirectoryNodes = <VMServiceObjectNode>[];
-    final userLibraryNodes = <VMServiceObjectNode>[];
-    final scriptNodes = <VMServiceObjectNode>[];
-    final classNodes = <VMServiceObjectNode>[];
-    final functionNodes = <VMServiceObjectNode>[];
-    final variableNodes = <VMServiceObjectNode>[];
-
-    final packageAndCoreLibLibraryNodes = <VMServiceObjectNode>[];
-    final packageAndCoreLibDirectoryNodes = <VMServiceObjectNode>[];
-
-    for (final child in children) {
-      if (child.object == null && child.script == null) {
-        // Child is a directory node. Treat it as if it were a library/script
-        // for sorting purposes.
-        if (child.name.startsWith(dartPrefix) ||
-            child.name.startsWith(packagePrefix)) {
-          packageAndCoreLibDirectoryNodes.add(child);
-        } else {
-          userDirectoryNodes.add(child);
-        }
-      } else {
-        switch (child.object.runtimeType) {
-          case ScriptRef:
-          case Script:
-            scriptNodes.add(child);
-            break;
-          case LibraryRef:
-          case Library:
-            final obj = child.object as LibraryRef;
-            if (obj.uri.startsWith(dartPrefix) ||
-                obj.uri.startsWith(packagePrefix)) {
-              packageAndCoreLibLibraryNodes.add(child);
-            } else {
-              userLibraryNodes.add(child);
-            }
-            break;
-          case ClassRef:
-          case Class:
-            classNodes.add(child);
-            break;
-          case FuncRef:
-          case Func:
-            functionNodes.add(child);
-            break;
-          case FieldRef:
-          case Field:
-            variableNodes.add(child);
-            break;
-          default:
-            throw StateError('Unexpected type: ${child.object.runtimeType}');
-        }
-      }
-      child._sortEntriesByType();
-    }
-
-    userDirectoryNodes.sort((a, b) {
-      return a.name.compareTo(b.name);
-    });
-
-    scriptNodes.sort((a, b) {
-      return a.name.compareTo(b.name);
-    });
-
-    userLibraryNodes.sort((a, b) {
-      return a.name.compareTo(b.name);
-    });
-
-    classNodes.sort((a, b) {
-      final objA = a.object as ClassRef;
-      final objB = b.object as ClassRef;
-      return objA.name.compareTo(objB.name);
-    });
-
-    functionNodes.sort((a, b) {
-      final objA = a.object as FuncRef;
-      final objB = b.object as FuncRef;
-      return objA.name.compareTo(objB.name);
-    });
-
-    variableNodes.sort((a, b) {
-      final objA = a.object as FieldRef;
-      final objB = b.object as FieldRef;
-      return objA.name.compareTo(objB.name);
-    });
-
-    packageAndCoreLibDirectoryNodes.sort((a, b) {
-      return a.name.compareTo(b.name);
-    });
-
-    packageAndCoreLibLibraryNodes.sort((a, b) {
-      return a.name.compareTo(b.name);
-    });
-
-    children
-      ..clear()
-      ..addAll([
-        ...userLibraryNodes,
-        ...userDirectoryNodes,
-        ...scriptNodes,
-        ...classNodes,
-        ...functionNodes,
-        ...variableNodes,
-        // We treat core libraries and packages as their own category as users
-        // are likely more interested in code within their own project.
-        // TODO(bkonyi): do we need custom google3 heuristics here?
-        ...packageAndCoreLibLibraryNodes,
-        ...packageAndCoreLibDirectoryNodes,
-      ]);
-  }
-
-  @override
-  int get hashCode => script?.uri.hashCode ?? object?.hashCode ?? name.hashCode;
-
-  @override
-  bool operator ==(Object other) {
-    if (other is! VMServiceObjectNode) return false;
-    final VMServiceObjectNode node = other;
-
-    return node.name == name &&
-        node.object == object &&
-        node.script?.uri == script?.uri;
-  }
-
-  @override
-  TreeNode<VMServiceObjectNode> shallowCopy() {
-    throw UnimplementedError(
-      'This method is not implemented. Implement if you '
-      'need to call `shallowCopy` on an instance of this class.',
-    );
-  }
-}
diff --git a/packages/devtools_app/lib/src/debugger/scripts.dart b/packages/devtools_app/lib/src/debugger/scripts.dart
new file mode 100644
index 00000000000..9dd95f4129e
--- /dev/null
+++ b/packages/devtools_app/lib/src/debugger/scripts.dart
@@ -0,0 +1,167 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:vm_service/vm_service.dart';
+
+import '../common_widgets.dart';
+import '../theme.dart';
+import '../tree.dart';
+import '../utils.dart';
+import 'debugger_controller.dart';
+import 'debugger_model.dart';
+
+const containerIcon = Icons.folder;
+const libraryIcon = Icons.insert_chart;
+double get listItemHeight => scaleByFontFactor(40.0);
+
+/// Picker that takes a list of scripts and allows selection of items.
+class ScriptPicker extends StatefulWidget {
+  const ScriptPicker({
+    Key key,
+    @required this.controller,
+    @required this.scripts,
+    @required this.onSelected,
+  }) : super(key: key);
+
+  final DebuggerController controller;
+  final List<ScriptRef> scripts;
+  final void Function(ScriptLocation scriptRef) onSelected;
+
+  @override
+  ScriptPickerState createState() => ScriptPickerState();
+}
+
+class ScriptPickerState extends State<ScriptPicker> {
+
+  List<ObjRef> _items = [];
+  List<FileNode> _rootScriptNodes;
+
+  @override
+  void initState() {
+    super.initState();
+
+    _updateScripts();
+  }
+
+  @override
+  void didUpdateWidget(ScriptPicker oldWidget) {
+    super.didUpdateWidget(oldWidget);
+
+    updateScripts();
+  }
+
+  void updateScripts() {
+    setState(_updateScripts);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    // Re-calculate the tree of scripts if necessary.
+    _rootScriptNodes ??= FileNode.createRootsFrom(_items);
+
+    return OutlineDecoration(
+      child: Column(
+        children: [
+          const AreaPaneHeader(
+            title: Text('Libraries'),
+            needsTopBorder: false,
+          ),
+          if (_isLoading) const CenteredCircularProgressIndicator(),
+          if (!_isLoading)
+            Expanded(
+              child: TreeView<FileNode>(
+                itemExtent: listItemHeight,
+                dataRoots: _rootScriptNodes,
+                dataDisplayProvider: (item, onTap) =>
+                    _displayProvider(context, item, onTap),
+              ),
+            ),
+        ],
+      ),
+    );
+  }
+
+  Widget _displayProvider(
+    BuildContext context,
+    FileNode node,
+    VoidCallback onTap,
+  ) {
+    return DevToolsTooltip(
+      tooltip: node.name,
+      child: Material(
+        child: InkWell(
+          onTap: () {
+            if (node.hasScript) {
+              _handleSelected(node.scriptRef);
+            }
+            onTap();
+          },
+          child: Row(
+            children: [
+              Icon(
+                node.hasScript ? libraryIcon : containerIcon,
+                size: defaultIconSize,
+              ),
+              const SizedBox(width: densePadding),
+              Expanded(
+                child: Column(
+                  mainAxisAlignment: MainAxisAlignment.center,
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    if (!node.hasScript)
+                      Text(
+                        node.name,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                      )
+                    else ...[
+                      Text(
+                        node.fileName,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                      ),
+                      Text(
+                        node.scriptRef.uri,
+                        style: Theme.of(context).subtleTextStyle,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                      ),
+                    ]
+                  ],
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  bool get _isLoading => widget.scripts.isEmpty;
+
+  void _updateScripts() {
+    _items = widget.scripts;
+    
+    // Remove the cached value here; it'll be re-computed the next time we need
+    // it.
+    _rootScriptNodes = null;
+  }
+
+  void _handleSelected(ObjRef ref) async {
+    if (ref is ScriptRef) {
+      widget.onSelected(ScriptLocation(ref));
+    } else if (ref is ClassRef) {
+      final obj = await widget.controller.getObject(ref);
+      final location = (obj as Class).location;
+      final script = await widget.controller.getScript(location.script);
+      final pos =
+          widget.controller.calculatePosition(script, location.tokenPos);
+
+      widget.onSelected(ScriptLocation(script, location: pos));
+    } else {
+      assert(false, 'unexpected object reference: ${ref.type}');
+    }
+  }
+}
diff --git a/packages/devtools_app/lib/src/debugger/variables.dart b/packages/devtools_app/lib/src/debugger/variables.dart
index ba97a38ffe1..df5335392fe 100644
--- a/packages/devtools_app/lib/src/debugger/variables.dart
+++ b/packages/devtools_app/lib/src/debugger/variables.dart
@@ -36,7 +36,7 @@ class Variables extends StatelessWidget {
           dataRoots: variables,
           dataDisplayProvider: (variable, onPressed) =>
               displayProvider(context, variable, onPressed, controller),
-          onItemSelected: (variable) => onItemPressed(variable, controller),
+          onItemPressed: (variable) => onItemPressed(variable, controller),
         );
       },
     );
@@ -65,7 +65,7 @@ class VariablesList extends StatelessWidget {
       dataRoots: lines,
       dataDisplayProvider: (variable, onPressed) =>
           displayProvider(context, variable, onPressed, controller),
-      onItemSelected: (variable) => onItemPressed(variable, controller),
+      onItemPressed: (variable) => onItemPressed(variable, controller),
     );
   }
 
@@ -101,7 +101,7 @@ class ExpandableVariable extends StatelessWidget {
           shrinkWrap: true,
           dataDisplayProvider: (variable, onPressed) =>
               displayProvider(context, variable, onPressed, debuggerController),
-          onItemSelected: (variable) =>
+          onItemPressed: (variable) =>
               onItemPressed(variable, debuggerController),
         );
       },
diff --git a/packages/devtools_app/lib/src/history_manager.dart b/packages/devtools_app/lib/src/history_manager.dart
index a2470251cec..0ce5c491ccc 100644
--- a/packages/devtools_app/lib/src/history_manager.dart
+++ b/packages/devtools_app/lib/src/history_manager.dart
@@ -52,11 +52,6 @@ class HistoryManager<T> {
     _current.value = _history[_historyIndex];
   }
 
-  /// Return the next value.
-  ///
-  /// Returns null if there is no next value.
-  T peekNext() => hasNext ? _history[_historyIndex + 1] : null;
-
   /// Remove the most recent historical item on the stack.
   ///
   /// If [current] is the last item on the stack when this method is called,
diff --git a/packages/devtools_app/lib/src/history_viewport.dart b/packages/devtools_app/lib/src/history_viewport.dart
index bd3c88bd05d..94ae69cb341 100644
--- a/packages/devtools_app/lib/src/history_viewport.dart
+++ b/packages/devtools_app/lib/src/history_viewport.dart
@@ -29,16 +29,12 @@ class HistoryViewport<T> extends StatelessWidget {
     @required this.contentBuilder,
     this.controls,
     this.generateTitle,
-    this.onChange,
-    this.historyEnabled = true,
   });
 
   final HistoryManager<T> history;
   final String Function(T) generateTitle;
   final List<Widget> controls;
   final Widget Function(BuildContext, T) contentBuilder;
-  final void Function(T, T) onChange;
-  final bool historyEnabled;
 
   @override
   Widget build(BuildContext context) {
@@ -63,40 +59,17 @@ class HistoryViewport<T> extends StatelessWidget {
       theme,
       child: Row(
         children: [
-          if (historyEnabled) ...[
-            ToolbarAction(
-              icon: Icons.chevron_left,
-              onPressed: history.hasPrevious
-                  ? () {
-                      history.moveBack();
-                      if (onChange != null) {
-                        onChange(
-                          history.current.value,
-                          history.peekNext(),
-                        );
-                      }
-                    }
-                  : null,
-            ),
-            ToolbarAction(
-              icon: Icons.chevron_right,
-              onPressed: history.hasNext
-                  ? () {
-                      final current = history.current.value;
-                      history.moveForward();
-                      if (onChange != null) {
-                        onChange(
-                          history.current.value,
-                          current,
-                        );
-                      }
-                    }
-                  : null,
-            ),
-            const SizedBox(width: denseSpacing),
-            const VerticalDivider(thickness: 1.0),
-            const SizedBox(width: defaultSpacing),
-          ],
+          ToolbarAction(
+            icon: Icons.chevron_left,
+            onPressed: history.hasPrevious ? history.moveBack : null,
+          ),
+          ToolbarAction(
+            icon: Icons.chevron_right,
+            onPressed: history.hasNext ? history.moveForward : null,
+          ),
+          const SizedBox(width: denseSpacing),
+          const VerticalDivider(thickness: 1.0),
+          const SizedBox(width: defaultSpacing),
           Expanded(
             child: Text(
               generateTitle == null
diff --git a/packages/devtools_app/lib/src/inspector/diagnostics_node.dart b/packages/devtools_app/lib/src/inspector/diagnostics_node.dart
index 24b726cd740..0e8a7c2e254 100644
--- a/packages/devtools_app/lib/src/inspector/diagnostics_node.dart
+++ b/packages/devtools_app/lib/src/inspector/diagnostics_node.dart
@@ -11,7 +11,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:vm_service/vm_service.dart';
 
-import '../debugger/debugger_model.dart';
 import '../enum_utils.dart';
 import '../ui/icons.dart';
 import '../utils.dart';
@@ -719,3 +718,13 @@ class InspectorSourceLocation {
     return SourcePosition(file: file, line: line - 1, column: column - 1);
   }
 }
+
+// TODO(jacobr): rename this class or merge with SourcePosition class in
+// debugger_model.dart
+class SourcePosition {
+  const SourcePosition({this.file, this.line, this.column});
+
+  final String file;
+  final int line;
+  final int column;
+}
diff --git a/packages/devtools_app/lib/src/inspector/inspector_service.dart b/packages/devtools_app/lib/src/inspector/inspector_service.dart
index 0140002efa0..36be37f03fd 100644
--- a/packages/devtools_app/lib/src/inspector/inspector_service.dart
+++ b/packages/devtools_app/lib/src/inspector/inspector_service.dart
@@ -17,7 +17,7 @@ import 'package:meta/meta.dart';
 import 'package:vm_service/vm_service.dart';
 
 import '../auto_dispose.dart';
-import '../debugger/debugger_model.dart';
+import '../debugger/debugger_model.dart' hide SourcePosition;
 import '../eval_on_dart_library.dart';
 import '../globals.dart';
 import '../utils.dart';
diff --git a/packages/devtools_app/lib/src/inspector/inspector_tree_controller.dart b/packages/devtools_app/lib/src/inspector/inspector_tree_controller.dart
index b544f1852f7..75f743585a0 100644
--- a/packages/devtools_app/lib/src/inspector/inspector_tree_controller.dart
+++ b/packages/devtools_app/lib/src/inspector/inspector_tree_controller.dart
@@ -260,7 +260,7 @@ class InspectorTreeController extends Object {
 
     selection = root
         .getRow(
-            (root.getRowIndex(selection) + indexOffset).clamp(0, numRows - 1))
+        (root.getRowIndex(selection) + indexOffset).clamp(0, numRows - 1))
         ?.node;
   }
 
@@ -405,7 +405,7 @@ class InspectorTreeController extends Object {
       if (row != null) {
         final rowRect = getBoundingBox(row);
         targetRect =
-            targetRect == null ? rowRect : targetRect.expandToInclude(rowRect);
+        targetRect == null ? rowRect : targetRect.expandToInclude(rowRect);
       }
     }
 
@@ -439,11 +439,11 @@ class InspectorTreeController extends Object {
   }
 
   InspectorTreeNode setupInspectorTreeNode(
-    InspectorTreeNode node,
-    RemoteDiagnosticsNode diagnosticsNode, {
-    @required bool expandChildren,
-    @required bool expandProperties,
-  }) {
+      InspectorTreeNode node,
+      RemoteDiagnosticsNode diagnosticsNode, {
+        @required bool expandChildren,
+        @required bool expandProperties,
+      }) {
     assert(expandChildren != null);
     assert(expandProperties != null);
     node.diagnostic = diagnosticsNode;
@@ -455,7 +455,7 @@ class InspectorTreeController extends Object {
         diagnosticsNode.inlineProperties.isNotEmpty) {
       if (diagnosticsNode.childrenReady || !diagnosticsNode.hasChildren) {
         final bool styleIsMultiline =
-            expandPropertiesByDefault(diagnosticsNode.style);
+        expandPropertiesByDefault(diagnosticsNode.style);
         setupChildren(
           diagnosticsNode,
           node,
@@ -472,12 +472,12 @@ class InspectorTreeController extends Object {
   }
 
   void setupChildren(
-    RemoteDiagnosticsNode parent,
-    InspectorTreeNode treeNode,
-    List<RemoteDiagnosticsNode> children, {
-    @required bool expandChildren,
-    @required bool expandProperties,
-  }) {
+      RemoteDiagnosticsNode parent,
+      InspectorTreeNode treeNode,
+      List<RemoteDiagnosticsNode> children, {
+        @required bool expandChildren,
+        @required bool expandProperties,
+      }) {
     assert(expandChildren != null);
     assert(expandProperties != null);
     treeNode.isExpanded = expandChildren;
diff --git a/packages/devtools_app/lib/src/performance/legacy/performance_model.dart b/packages/devtools_app/lib/src/performance/legacy/performance_model.dart
index f69d5d917a9..51deaae0d59 100644
--- a/packages/devtools_app/lib/src/performance/legacy/performance_model.dart
+++ b/packages/devtools_app/lib/src/performance/legacy/performance_model.dart
@@ -681,8 +681,7 @@ abstract class LegacyTimelineEvent extends TreeNode<LegacyTimelineEvent>
   }
 
   @override
-  void addChild(LegacyTimelineEvent child, {int index}) {
-    assert(index == null);
+  void addChild(LegacyTimelineEvent child) {
     void _putChildInTree(LegacyTimelineEvent root) {
       // [root] is a leaf. Add child here.
       if (root.children.isEmpty) {
@@ -971,8 +970,7 @@ class LegacyAsyncTimelineEvent extends LegacyTimelineEvent {
   }
 
   @override
-  void addChild(LegacyTimelineEvent child, {int index}) {
-    assert(index == null);
+  void addChild(LegacyTimelineEvent child) {
     final LegacyAsyncTimelineEvent _child = child;
     // Short circuit if we are using an explicit parentId.
     if (_child.hasExplicitParent &&
diff --git a/packages/devtools_app/lib/src/performance/performance_model.dart b/packages/devtools_app/lib/src/performance/performance_model.dart
index dddb019ddf3..ba34878012e 100644
--- a/packages/devtools_app/lib/src/performance/performance_model.dart
+++ b/packages/devtools_app/lib/src/performance/performance_model.dart
@@ -789,8 +789,7 @@ abstract class TimelineEvent extends TreeNode<TimelineEvent>
   }
 
   @override
-  void addChild(TimelineEvent child, {int index}) {
-    assert(index == null);
+  void addChild(TimelineEvent child) {
     void _putChildInTree(TimelineEvent root) {
       // [root] is a leaf. Add child here.
       if (root.children.isEmpty) {
@@ -1103,8 +1102,7 @@ class AsyncTimelineEvent extends TimelineEvent {
   }
 
   @override
-  void addChild(TimelineEvent child, {int index}) {
-    assert(index == null);
+  void addChild(TimelineEvent child) {
     final AsyncTimelineEvent _child = child;
     // Short circuit if we are using an explicit parentId.
     if (_child.hasExplicitParent &&
diff --git a/packages/devtools_app/lib/src/theme.dart b/packages/devtools_app/lib/src/theme.dart
index dd185631607..0b78d2837d5 100644
--- a/packages/devtools_app/lib/src/theme.dart
+++ b/packages/devtools_app/lib/src/theme.dart
@@ -421,10 +421,6 @@ extension ThemeDataExtension on ThemeData {
   TextStyle get subtleFixedFontStyle =>
       fixedFontStyle.copyWith(color: unselectedWidgetColor);
 
-  TextStyle get toolTipFixedFontStyle => fixedFontStyle.copyWith(
-        color: colorScheme.tooltipTextColor,
-      );
-
   TextStyle get devToolsTitleStyle =>
       textTheme.headline6.copyWith(color: Colors.white);
 
diff --git a/packages/devtools_app/lib/src/tree.dart b/packages/devtools_app/lib/src/tree.dart
index 4108e1ccf76..7259f49096c 100644
--- a/packages/devtools_app/lib/src/tree.dart
+++ b/packages/devtools_app/lib/src/tree.dart
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
-
 import 'package:flutter/material.dart' hide Stack;
 
 import 'collapsible_mixin.dart';
@@ -14,8 +12,7 @@ class TreeView<T extends TreeNode<T>> extends StatefulWidget {
   const TreeView({
     this.dataRoots,
     this.dataDisplayProvider,
-    this.onItemSelected,
-    this.onItemExpanded,
+    this.onItemPressed,
     this.shrinkWrap = false,
     this.itemExtent,
     this.onTraverse,
@@ -33,14 +30,7 @@ class TreeView<T extends TreeNode<T>> extends StatefulWidget {
 
   final Widget Function(T, VoidCallback) dataDisplayProvider;
 
-  /// Invoked when a tree node is selected. If [onItemExpanded] is not
-  /// provided, this method will also be called when the expand button is
-  /// tapped.
-  final FutureOr<void> Function(T) onItemSelected;
-
-  /// If provided, this method will be called when the expand button is tapped.
-  /// Otherwise, [onItemSelected] will be invoked, if provided.
-  final FutureOr<void> Function(T) onItemExpanded;
+  final void Function(T) onItemPressed;
 
   final double itemExtent;
 
@@ -87,33 +77,20 @@ class _TreeViewState<T extends TreeNode<T>> extends State<TreeView<T>>
           item,
           buildDisplay: (onPressed) =>
               widget.dataDisplayProvider(item, onPressed),
-          onItemSelected: _onItemSelected,
-          onItemExpanded: _onItemExpanded,
+          onItemPressed: _onItemPressed,
         );
       },
     );
   }
 
   // TODO(kenz): animate expansions and collapses.
-  void _onItemSelected(T item) async {
-    // Order of execution matters for the below calls.
-    if (widget.onItemExpanded == null && item.isExpandable) {
-      item.toggleExpansion();
-    }
-    if (widget.onItemSelected != null) {
-      await widget.onItemSelected(item);
-    }
-    _updateItems();
-  }
+  void _onItemPressed(T item) {
+    if (!item.isExpandable) return;
 
-  void _onItemExpanded(T item) async {
-    if (item.isExpandable) {
-      item.toggleExpansion();
-    }
-    if (widget.onItemExpanded != null) {
-      await widget.onItemExpanded(item);
-    } else if (widget.onItemSelected != null) {
-      await widget.onItemSelected(item);
+    // Order of execution matters for the below calls.
+    item.toggleExpansion();
+    if (widget.onItemPressed != null) {
+      widget.onItemPressed(item);
     }
     _updateItems();
   }
@@ -129,19 +106,13 @@ class _TreeViewState<T extends TreeNode<T>> extends State<TreeView<T>>
 }
 
 class TreeViewItem<T extends TreeNode<T>> extends StatefulWidget {
-  const TreeViewItem(
-    this.data, {
-    this.buildDisplay,
-    this.onItemExpanded,
-    this.onItemSelected,
-  });
+  const TreeViewItem(this.data, {this.buildDisplay, this.onItemPressed});
 
   final T data;
 
   final Widget Function(VoidCallback onPressed) buildDisplay;
 
-  final void Function(T) onItemSelected;
-  final void Function(T) onItemExpanded;
+  final void Function(T) onItemPressed;
 
   @override
   _TreeViewItemState<T> createState() => _TreeViewItemState<T>();
@@ -153,27 +124,23 @@ class _TreeViewItemState<T extends TreeNode<T>> extends State<TreeViewItem<T>>
   Widget build(BuildContext context) {
     return Padding(
       padding: EdgeInsets.only(left: nodeIndent(widget.data)),
-      child: Container(
-        color:
-            widget.data.isSelected ? Theme.of(context).selectedRowColor : null,
-        child: Row(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            widget.data.isExpandable
-                ? InkWell(
-                    onTap: _onExpanded,
-                    child: RotationTransition(
-                      turns: expandArrowAnimation,
-                      child: Icon(
-                        Icons.keyboard_arrow_down,
-                        size: defaultIconSize,
-                      ),
+      child: Row(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          widget.data.isExpandable
+              ? InkWell(
+                  onTap: _onPressed,
+                  child: RotationTransition(
+                    turns: expandArrowAnimation,
+                    child: Icon(
+                      Icons.arrow_drop_down,
+                      size: defaultIconSize,
                     ),
-                  )
-                : SizedBox(width: defaultIconSize),
-            Expanded(child: widget.buildDisplay(_onSelected)),
-          ],
-        ),
+                  ),
+                )
+              : SizedBox(width: defaultIconSize),
+          Expanded(child: widget.buildDisplay(_onPressed)),
+        ],
       ),
     );
   }
@@ -191,13 +158,8 @@ class _TreeViewItemState<T extends TreeNode<T>> extends State<TreeViewItem<T>>
     return dataObject.level * defaultSpacing;
   }
 
-  void _onExpanded() {
-    widget?.onItemExpanded(widget.data);
-    setExpanded(widget.data.isExpanded);
-  }
-
-  void _onSelected() {
-    widget?.onItemSelected(widget.data);
+  void _onPressed() {
+    widget.onItemPressed(widget.data);
     setExpanded(widget.data.isExpanded);
   }
 }
diff --git a/packages/devtools_app/lib/src/trees.dart b/packages/devtools_app/lib/src/trees.dart
index a4523067f83..95f6e105e63 100644
--- a/packages/devtools_app/lib/src/trees.dart
+++ b/packages/devtools_app/lib/src/trees.dart
@@ -43,9 +43,6 @@ abstract class TreeNode<T extends TreeNode<T>> {
 
   bool get isRoot => parent == null;
 
-  bool get isSelected => _selected;
-  bool _selected = false;
-
   T get root {
     if (_root != null) {
       return _root;
@@ -81,22 +78,15 @@ abstract class TreeNode<T extends TreeNode<T>> {
     _isExpanded = true;
   }
 
-  void select() {
-    _selected = true;
-  }
-
-  void unselect() {
-    _selected = false;
-  }
-
   // TODO(jacobr): cache the value of whether the node should be shown
   // so that lookups on this class are O(1) invalidating the cache when nodes
   // up the tree are expanded and collapsed.
   /// Whether this node should be shown in the tree.
   ///
   /// When using this, consider caching the value. It is O([level]) to compute.
-  bool shouldShow() =>
-      parent == null || (parent.isExpanded && parent.shouldShow());
+  bool shouldShow() {
+    return parent == null || (parent.isExpanded && parent.shouldShow());
+  }
 
   void collapse() {
     _isExpanded = false;
@@ -109,23 +99,10 @@ abstract class TreeNode<T extends TreeNode<T>> {
   /// Override to handle pressing on a Leaf node.
   void leaf() {}
 
-  void addChild(T child, {int index}) {
-    index ??= children.length;
-    assert(index <= children.length);
-    children.insert(index, child);
+  void addChild(T child) {
+    children.add(child);
     child.parent = this;
-    child.index = index;
-    for (int i = index + 1; i < children.length; ++i) {
-      children[i].index++;
-    }
-  }
-
-  T removeChildAtIndex(int index) {
-    assert(index < children.length);
-    for (int i = index + 1; i < children.length; ++i) {
-      children[i].index--;
-    }
-    return children.removeAt(index);
+    child.index = children.length - 1;
   }
 
   void addAllChildren(List<T> children) {
@@ -139,12 +116,6 @@ abstract class TreeNode<T extends TreeNode<T>> {
     });
   }
 
-  /// Expands this node and each parent node recursively.
-  void expandAscending() {
-    expand();
-    parent?.expandAscending();
-  }
-
   /// Collapses this node and all of its children (cascading).
   void collapseCascading() {
     breadthFirstTraversal<T>(this, action: (T node) {
diff --git a/packages/devtools_app/lib/src/vm_developer/vm_service_private_extensions.dart b/packages/devtools_app/lib/src/vm_developer/vm_service_private_extensions.dart
index 9dc09dbb8c5..44328c217f4 100644
--- a/packages/devtools_app/lib/src/vm_developer/vm_service_private_extensions.dart
+++ b/packages/devtools_app/lib/src/vm_developer/vm_service_private_extensions.dart
@@ -32,7 +32,3 @@ extension IsolatePrivateViewExtension on Isolate {
   int get newSpaceCapacity => json['_heaps']['new']['capacity'];
   int get oldSpaceCapacity => json['_heaps']['old']['capacity'];
 }
-
-extension ClassPrivateViewExtension on Class {
-  String get vmName => json['_vmName'];
-}
diff --git a/packages/devtools_app/lib/src/vm_service_wrapper.dart b/packages/devtools_app/lib/src/vm_service_wrapper.dart
index 49a3d181eed..0b6d85c074a 100644
--- a/packages/devtools_app/lib/src/vm_service_wrapper.dart
+++ b/packages/devtools_app/lib/src/vm_service_wrapper.dart
@@ -1266,24 +1266,4 @@ extension VmServicePrivate on VmServiceWrapper {
         isolateId: isolateId,
         parser: PortList.parse,
       );
-
-  Future<InstanceRef> getReachableSize(String isolateId, String targetId) =>
-      _privateRpcInvoke(
-        'getReachableSize',
-        isolateId: isolateId,
-        args: {
-          'targetId': targetId,
-        },
-        parser: InstanceRef.parse,
-      );
-
-  Future<InstanceRef> getRetainedSize(String isolateId, String targetId) =>
-      _privateRpcInvoke(
-        'getRetainedSize',
-        isolateId: isolateId,
-        args: {
-          'targetId': targetId,
-        },
-        parser: InstanceRef.parse,
-      );
 }
diff --git a/packages/devtools_app/macos/Runner.xcodeproj/project.pbxproj b/packages/devtools_app/macos/Runner.xcodeproj/project.pbxproj
index a4d00fa9693..bc03301f8ac 100644
--- a/packages/devtools_app/macos/Runner.xcodeproj/project.pbxproj
+++ b/packages/devtools_app/macos/Runner.xcodeproj/project.pbxproj
@@ -308,9 +308,14 @@
 			files = (
 			);
 			inputPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-Runner/Pods-Runner-frameworks.sh",
+				"${BUILT_PRODUCTS_DIR}/file_selector_macos/file_selector_macos.framework",
+				"${BUILT_PRODUCTS_DIR}/url_launcher_macos/url_launcher_macos.framework",
 			);
 			name = "[CP] Embed Pods Frameworks";
 			outputPaths = (
+				"${TARGET_BUILD_DIR}/${FRAMEWORKS_FOLDER_PATH}/file_selector_macos.framework",
+				"${TARGET_BUILD_DIR}/${FRAMEWORKS_FOLDER_PATH}/url_launcher_macos.framework",
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
diff --git a/packages/devtools_app/test/debugger_controller_test.dart b/packages/devtools_app/test/debugger_controller_test.dart
index 466518f1f81..db5d19bc0b4 100644
--- a/packages/devtools_app/test/debugger_controller_test.dart
+++ b/packages/devtools_app/test/debugger_controller_test.dart
@@ -97,7 +97,7 @@ void main() {
       expect(history.current.value, ref1);
     });
 
-    test('moveForward', () {
+    test('moveBack', () {
       history.pushEntry(ref1);
       history.pushEntry(ref2);
 
@@ -257,9 +257,7 @@ void main() {
     DebuggerController debuggerController;
 
     setUp(() {
-      debuggerController = TestDebuggerController(
-        initialSwitchToIsolate: false,
-      );
+      debuggerController = DebuggerController(initialSwitchToIsolate: false);
       debuggerController.parsedScript.value = ParsedScript(
         script: testScript,
         highlighter: null,
diff --git a/packages/devtools_app/test/debugger_evalution_test.dart b/packages/devtools_app/test/debugger_evalution_test.dart
index b1bb5c0d09d..2ac24fa1bd2 100644
--- a/packages/devtools_app/test/debugger_evalution_test.dart
+++ b/packages/devtools_app/test/debugger_evalution_test.dart
@@ -26,7 +26,6 @@ void main() {
   setUp(() async {
     isAlive = Disposable();
     await env.setupEnvironment();
-    debuggerController = TestDebuggerController();
     eval = EvalOnDartLibrary(
         'package:flutter_app/src/autocomplete.dart', serviceManager.service,
         disableBreakpoints: false);
diff --git a/packages/devtools_app/test/debugger_screen_test.dart b/packages/devtools_app/test/debugger_screen_test.dart
index 7eb37488672..fd005c9aae7 100644
--- a/packages/devtools_app/test/debugger_screen_test.dart
+++ b/packages/devtools_app/test/debugger_screen_test.dart
@@ -10,7 +10,6 @@ import 'package:devtools_app/src/debugger/controls.dart';
 import 'package:devtools_app/src/debugger/debugger_controller.dart';
 import 'package:devtools_app/src/debugger/debugger_model.dart';
 import 'package:devtools_app/src/debugger/debugger_screen.dart';
-import 'package:devtools_app/src/debugger/program_explorer_model.dart';
 import 'package:devtools_app/src/globals.dart';
 import 'package:devtools_app/src/service_manager.dart';
 import 'package:devtools_test/mocks.dart';
@@ -209,7 +208,7 @@ void main() {
         // this so that forcing a scroll event is no longer necessary. Remove
         // once the change is in the stable release.
         debuggerController.showScriptLocation(ScriptLocation(mockScriptRef,
-            location: const SourcePosition(line: 50, column: 50)));
+            location: SourcePosition(line: 50, column: 50)));
         await tester.pumpAndSettle();
 
         expect(find.byType(Scrollbar), findsNWidgets(2));
@@ -224,7 +223,7 @@ void main() {
       }, skip: !Platform.isMacOS);
     });
 
-    testWidgetsWithWindowSize('File Explorer hidden', windowSize,
+    testWidgetsWithWindowSize('Libraries hidden', windowSize,
         (WidgetTester tester) async {
       final scripts = [
         ScriptRef(uri: 'package:/test/script.dart', id: 'test-script')
@@ -233,40 +232,27 @@ void main() {
       when(debuggerController.sortedScripts).thenReturn(ValueNotifier(scripts));
       when(debuggerController.showFileOpener).thenReturn(ValueNotifier(false));
 
-      // File Explorer view is hidden
-      when(debuggerController.fileExplorerVisible)
+      // Libraries view is hidden
+      when(debuggerController.librariesVisible)
           .thenReturn(ValueNotifier(false));
       await pumpDebuggerScreen(tester, debuggerController);
-      expect(find.text('File Explorer'), findsOneWidget);
+      expect(find.text('Libraries'), findsOneWidget);
     });
 
-    testWidgetsWithWindowSize('File Explorer visible', windowSize,
+    testWidgetsWithWindowSize('Libraries visible', windowSize,
         (WidgetTester tester) async {
       final scripts = [
         ScriptRef(uri: 'package:test/script.dart', id: 'test-script')
       ];
 
       when(debuggerController.sortedScripts).thenReturn(ValueNotifier(scripts));
-      when(debuggerController.programExplorerController.rootObjectNodes)
-          .thenReturn(
-        ValueNotifier(
-          [
-            VMServiceObjectNode(
-              debuggerController.programExplorerController,
-              'package:test',
-              null,
-            ),
-          ],
-        ),
-      );
       when(debuggerController.showFileOpener).thenReturn(ValueNotifier(false));
 
-      // File Explorer view is shown
-      when(debuggerController.fileExplorerVisible)
-          .thenReturn(ValueNotifier(true));
+      // Libraries view is shown
+      when(debuggerController.librariesVisible).thenReturn(ValueNotifier(true));
       await pumpDebuggerScreen(tester, debuggerController);
-      // One for the button and one for the title of the File Explorer view.
-      expect(find.text('File Explorer'), findsNWidgets(2));
+      // One for the button and one for the title of the Libraries view.
+      expect(find.text('Libraries'), findsNWidgets(2));
 
       // test for items in the libraries tree
       expect(find.text(scripts.first.uri.split('/').first), findsOneWidget);
@@ -290,7 +276,7 @@ void main() {
       final breakpointsWithLocation = [
         BreakpointAndSourcePosition.create(
           breakpoints.first,
-          const SourcePosition(line: 10, column: 1),
+          SourcePosition(line: 10, column: 1),
         )
       ];
 
@@ -536,7 +522,7 @@ void main() {
             ),
             kind: FrameKind.kRegular,
           ),
-          position: const SourcePosition(
+          position: SourcePosition(
             line: 1,
             column: 10,
           ),
diff --git a/packages/devtools_app/test/inspector_tree_test.dart b/packages/devtools_app/test/inspector_tree_test.dart
index 0fd72a96f67..0016831e35e 100644
--- a/packages/devtools_app/test/inspector_tree_test.dart
+++ b/packages/devtools_app/test/inspector_tree_test.dart
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:devtools_app/src/debugger/debugger_controller.dart';
 import 'package:devtools_app/src/globals.dart';
 import 'package:devtools_app/src/inspector/inspector_service.dart';
 import 'package:devtools_app/src/inspector/inspector_tree.dart';
@@ -12,6 +13,7 @@ import 'package:devtools_test/mocks.dart';
 import 'package:devtools_test/utils.dart';
 import 'package:devtools_test/wrappers.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart' hide Fake;
 import 'package:mockito/mockito.dart';
 
@@ -37,7 +39,7 @@ void main() {
           onNodeAdded: (_, __) {},
           onClientActiveChange: (_) {},
         );
-      final debuggerController = TestDebuggerController();
+      final debuggerController = DebuggerController();
       await tester.pumpWidget(wrap(InspectorTree(
         controller: controller,
         debuggerController: debuggerController,
@@ -76,7 +78,7 @@ void main() {
       final treeController = inspectorTreeControllerFromNode(diagnosticNode);
       await tester.pumpWidget(wrap(InspectorTree(
         controller: treeController,
-        debuggerController: TestDebuggerController(),
+        debuggerController: DebuggerController(),
       )));
 
       expect(find.richText('Text: "Content"'), findsOneWidget);
@@ -98,7 +100,7 @@ void main() {
       final treeController = inspectorTreeControllerFromNode(diagnosticNode);
       await tester.pumpWidget(wrap(InspectorTree(
         controller: treeController,
-        debuggerController: TestDebuggerController(),
+        debuggerController: DebuggerController(),
       )));
 
       expect(find.richText('Text: "Rich text"'), findsOneWidget);
@@ -116,7 +118,7 @@ void main() {
       await tester.pumpWidget(
         wrap(InspectorTree(
           controller: treeController,
-          debuggerController: TestDebuggerController(),
+          debuggerController: DebuggerController(),
         )),
       );
 
diff --git a/packages/devtools_test/lib/mocks.dart b/packages/devtools_test/lib/mocks.dart
index cf8ec8444ae..23a8f2b064c 100644
--- a/packages/devtools_test/lib/mocks.dart
+++ b/packages/devtools_test/lib/mocks.dart
@@ -660,16 +660,6 @@ class MockPerformanceController extends Mock implements PerformanceController {}
 class MockProfilerScreenController extends Mock
     implements ProfilerScreenController {}
 
-class TestDebuggerController extends DebuggerController {
-  TestDebuggerController({bool initialSwitchToIsolate = true})
-      : super(initialSwitchToIsolate: initialSwitchToIsolate);
-
-  @override
-  ProgramExplorerController get programExplorerController =>
-      _explorerController;
-  final _explorerController = MockProgramExplorerController.withDefaults();
-}
-
 class MockDebuggerController extends Mock implements DebuggerController {
   MockDebuggerController();
 
@@ -681,8 +671,6 @@ class MockDebuggerController extends Mock implements DebuggerController {
     when(debuggerController.isSystemIsolate).thenReturn(false);
     when(debuggerController.breakpointsWithLocation)
         .thenReturn(ValueNotifier([]));
-    when(debuggerController.fileExplorerVisible)
-        .thenReturn(ValueNotifier(false));
     when(debuggerController.currentScriptRef).thenReturn(ValueNotifier(null));
     when(debuggerController.sortedScripts).thenReturn(ValueNotifier([]));
     when(debuggerController.selectedBreakpoint).thenReturn(ValueNotifier(null));
@@ -699,24 +687,6 @@ class MockDebuggerController extends Mock implements DebuggerController {
         .thenReturn(ValueNotifier<ParsedScript>(null));
     return debuggerController;
   }
-
-  @override
-  final programExplorerController =
-      MockProgramExplorerController.withDefaults();
-}
-
-class MockProgramExplorerController extends Mock
-    implements ProgramExplorerController {
-  MockProgramExplorerController();
-
-  factory MockProgramExplorerController.withDefaults() {
-    final controller = MockProgramExplorerController();
-    when(controller.initialized).thenReturn(ValueNotifier(true));
-    when(controller.rootObjectNodes).thenReturn(ValueNotifier([]));
-    when(controller.outlineNodes).thenReturn(ValueNotifier([]));
-
-    return controller;
-  }
 }
 
 class MockVM extends Mock implements VM {}

From 51955d36ee0c87e20b4a02e13fd265627cf8f83c Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 09:10:03 -0700
Subject: [PATCH 6/9] remove import

---
 packages/devtools_app/lib/devtools_app.dart | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/devtools_app/lib/devtools_app.dart b/packages/devtools_app/lib/devtools_app.dart
index a4fca7b44a6..732742b5ba1 100644
--- a/packages/devtools_app/lib/devtools_app.dart
+++ b/packages/devtools_app/lib/devtools_app.dart
@@ -9,7 +9,6 @@ export 'src/charts/treemap.dart';
 export 'src/connected_app.dart';
 export 'src/console_service.dart';
 export 'src/debugger/debugger_controller.dart';
-export 'src/debugger/program_explorer_controller.dart';
 export 'src/debugger/span_parser.dart';
 export 'src/debugger/syntax_highlighter.dart';
 export 'src/error_badge_manager.dart';

From 1a87c12d30db12ef2f3278568a716ea1b231d65f Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 09:24:03 -0700
Subject: [PATCH 7/9] remove import

---
 packages/devtools_app/test/debugger_evalution_test.dart | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/devtools_app/test/debugger_evalution_test.dart b/packages/devtools_app/test/debugger_evalution_test.dart
index 2ac24fa1bd2..bc89e03de6d 100644
--- a/packages/devtools_app/test/debugger_evalution_test.dart
+++ b/packages/devtools_app/test/debugger_evalution_test.dart
@@ -10,7 +10,6 @@ import 'package:devtools_app/src/ui/search.dart';
 import 'package:devtools_app/src/utils.dart';
 import 'package:devtools_test/flutter_test_driver.dart';
 import 'package:devtools_test/flutter_test_environment.dart';
-import 'package:devtools_test/mocks.dart';
 import 'package:devtools_test/utils.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:pedantic/pedantic.dart';

From 0061e49482ae4b29f610f8fa6f49027f36a7b413 Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 09:37:31 -0700
Subject: [PATCH 8/9] fix test

---
 packages/devtools_app/test/debugger_evalution_test.dart | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/devtools_app/test/debugger_evalution_test.dart b/packages/devtools_app/test/debugger_evalution_test.dart
index bc89e03de6d..7074b65ef19 100644
--- a/packages/devtools_app/test/debugger_evalution_test.dart
+++ b/packages/devtools_app/test/debugger_evalution_test.dart
@@ -25,6 +25,7 @@ void main() {
   setUp(() async {
     isAlive = Disposable();
     await env.setupEnvironment();
+    debuggerController = DebuggerController();
     eval = EvalOnDartLibrary(
         'package:flutter_app/src/autocomplete.dart', serviceManager.service,
         disableBreakpoints: false);

From 8616c91c054fcfbc87edf97cc9189d13215afbfe Mon Sep 17 00:00:00 2001
From: Kenzie Schmoll <kenzieschmoll@google.com>
Date: Fri, 1 Oct 2021 10:11:43 -0700
Subject: [PATCH 9/9] fix mock

---
 packages/devtools_test/lib/mocks.dart | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/devtools_test/lib/mocks.dart b/packages/devtools_test/lib/mocks.dart
index 23a8f2b064c..7dcf3626297 100644
--- a/packages/devtools_test/lib/mocks.dart
+++ b/packages/devtools_test/lib/mocks.dart
@@ -671,6 +671,7 @@ class MockDebuggerController extends Mock implements DebuggerController {
     when(debuggerController.isSystemIsolate).thenReturn(false);
     when(debuggerController.breakpointsWithLocation)
         .thenReturn(ValueNotifier([]));
+    when(debuggerController.librariesVisible).thenReturn(ValueNotifier(false));
     when(debuggerController.currentScriptRef).thenReturn(ValueNotifier(null));
     when(debuggerController.sortedScripts).thenReturn(ValueNotifier([]));
     when(debuggerController.selectedBreakpoint).thenReturn(ValueNotifier(null));