Provide an app entrypoint to DWDS (#2047)

Author: elliette

dwds/CHANGELOG.md

@@ -1,4 +1,5 @@
-## 18.0.3-dev
+## 19.0.0-dev
+- Allow clients to specify the connected app's entrypoint file. - [#2047](https://github.com/dart-lang/webdev/pull/2047)
 
 ## 18.0.2
 

dwds/lib/src/debugging/libraries.dart

@@ -32,8 +32,15 @@ class LibraryHelper extends Domain {
     // TODO: read entrypoint from app metadata.
     // Issue: https://github.com/dart-lang/webdev/issues/1290
     final libraries = await libraryRefs;
-    _rootLib = libraries
-        .firstWhereOrNull((lib) => lib.name?.contains('org-dartlang') ?? false);
+    if (globalLoadStrategy.appEntrypoint != null) {
+      _rootLib = libraries.firstWhereOrNull(
+        (lib) => Uri.parse(lib.uri ?? '') == globalLoadStrategy.appEntrypoint,
+      );
+    }
+    _rootLib = _rootLib ??
+        libraries.firstWhereOrNull(
+          (lib) => lib.name?.contains('org-dartlang') ?? false,
+        );
     _rootLib = _rootLib ??
         libraries
             .firstWhereOrNull((lib) => lib.name?.contains('main') ?? false);