SemanticOwner should dispatch creation and disposal events (#138388)

packages/flutter/lib/src/semantics/semantics.dart

@@ -3281,7 +3281,17 @@ class SemanticsOwner extends ChangeNotifier {
   /// Creates a [SemanticsOwner] that manages zero or more [SemanticsNode] objects.
   SemanticsOwner({
     required this.onSemanticsUpdate,
-  });
+  }){
+    // TODO(polina-c): stop duplicating code across disposables
+    // https://github.com/flutter/flutter/issues/137435
+    if (kFlutterMemoryAllocationsEnabled) {
+      MemoryAllocations.instance.dispatchObjectCreated(
+        library: 'package:flutter/semantics.dart',
+        className: '$SemanticsOwner',
+        object: this,
+      );
+    }
+  }
 
   /// The [onSemanticsUpdate] callback is expected to dispatch [SemanticsUpdate]s
   /// to the [FlutterView] that is associated with this [PipelineOwner] and/or
@@ -3302,6 +3312,9 @@ class SemanticsOwner extends ChangeNotifier {
 
   @override
   void dispose() {
+    if (kFlutterMemoryAllocationsEnabled) {
+      MemoryAllocations.instance.dispatchObjectDisposed(object: this);
+    }
     _dirtyNodes.clear();
     _nodes.clear();
     _detachedNodes.clear();

packages/flutter/test/semantics/semantics_test.dart

@@ -6,6 +6,7 @@ import 'dart:ui';
 
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import '../rendering/rendering_tester.dart';
@@ -965,6 +966,16 @@ void main() {
     expect(config.onTap, same(onTap));
     expect(config.customSemanticsActions[customAction], same(onCustomAction));
   });
+
+  test('SemanticsOwner dispatches memory events', () async {
+    await expectLater(
+      await memoryEvents(() =>  SemanticsOwner(
+        onSemanticsUpdate: (SemanticsUpdate update) {},
+      ).dispose(), SemanticsOwner),
+      areCreateAndDispose,
+    );
+  });
+
 }
 
 class TestRender extends RenderProxyBox {