Support parameters in InternalTag (#7060)

* Support parameters in InternalTag

- This adds support for parameters in InternalTag.

* Address comments.

Author: dstrain115

cirq-google/cirq_google/ops/internal_tag.py

@@ -17,8 +17,6 @@
 from cirq import value
 from cirq_google.api.v2 import program_pb2
 
-# from cirq_google.serialization import arg_func_langs
-
 
 @value.value_equality
 class InternalTag:
@@ -62,18 +60,31 @@ def _value_equality_values_(self):
         return (self.name, self.package, tag_args_eq_values)
 
     def to_proto(self, msg: Optional[program_pb2.Tag] = None) -> program_pb2.Tag:
+        # To avoid circular import
+        from cirq_google.serialization import arg_func_langs
+
         if msg is None:
             msg = program_pb2.Tag()
         msg.internal_tag.tag_name = self.name
         msg.internal_tag.tag_package = self.package
+        for k, v in self.tag_args.items():
+            arg_func_langs.arg_to_proto(
+                v, out=msg.internal_tag.tag_args[k], arg_function_language='exp'
+            )
         return msg
 
     @staticmethod
     def from_proto(msg: program_pb2.Tag) -> 'InternalTag':
+        # To avoid circular import
+        from cirq_google.serialization import arg_func_langs
+
         if msg.WhichOneof("tag") != "internal_tag":
             raise ValueError(f"Message is not a InternalTag, {msg}")
+
+        kw_dict = {}
+        for k, v in msg.internal_tag.tag_args.items():
+            kw_dict[k] = arg_func_langs.arg_from_proto(v, arg_function_language='exp')
+
         return InternalTag(
-            name=msg.internal_tag.tag_name,
-            package=msg.internal_tag.tag_package,
-            **msg.internal_tag.tag_args,
+            name=msg.internal_tag.tag_name, package=msg.internal_tag.tag_package, **kw_dict
         )

cirq-google/cirq_google/ops/internal_tag_test.py

@@ -58,7 +58,7 @@ def test_internal_tag_with_hashable_args_is_hashable():
 
 
 def test_proto():
-    tag = cirq_google.InternalTag(name="TagWithNoParams", package='test')
+    tag = cirq_google.InternalTag(name="TagWithNoParams", package='test', param1=2.5)
     msg = tag.to_proto()
     assert tag == cirq_google.InternalTag.from_proto(msg)