Make Route dispatching memory events. (#133721)

Author: polina-c

packages/flutter/lib/src/widgets/navigator.dart

@@ -140,7 +140,15 @@ abstract class Route<T> {
   ///
   /// If the [settings] are not provided, an empty [RouteSettings] object is
   /// used instead.
-  Route({ RouteSettings? settings }) : _settings = settings ?? const RouteSettings();
+  Route({ RouteSettings? settings }) : _settings = settings ?? const RouteSettings() {
+    if (kFlutterMemoryAllocationsEnabled) {
+      MemoryAllocations.instance.dispatchObjectCreated(
+        library: 'package:flutter/widgets.dart',
+        className: '$Route<$T>',
+        object: this,
+      );
+    }
+  }
 
   /// The navigator that the route is in, if any.
   NavigatorState? get navigator => _navigator;
@@ -503,6 +511,9 @@ abstract class Route<T> {
   void dispose() {
     _navigator = null;
     _restorationScopeId.dispose();
+    if (kFlutterMemoryAllocationsEnabled) {
+      MemoryAllocations.instance.dispatchObjectDisposed(object: this);
+    }
   }
 
   /// Whether this route is the top-most route on the navigator.

packages/flutter/test/material/app_test.dart

@@ -338,7 +338,10 @@ void main() {
   // TODO(polina-c): remove after fixing
   // https://github.com/flutter/flutter/issues/133695
   leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?> {'ValueNotifier<String?>': 3},
+    notDisposedAllowList: <String, int?> {
+      'ValueNotifier<String?>': 3,
+      'MaterialPageRoute<dynamic>': 3,
+    },
   ));
 
   testWidgetsWithLeakTracking('Make sure initialRoute is only used the first time', (WidgetTester tester) async {

packages/flutter/test/widgets/navigator_test.dart

@@ -10,6 +10,7 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
 import 'navigator_utils.dart';
 import 'observer_tester.dart';
@@ -627,6 +628,41 @@ void main() {
     expect(observations[2].previous, '/A');
   });
 
+  testWidgetsWithLeakTracking('$Route  dispatches memory events', (WidgetTester tester) async {
+    Future<void> createAndDisposeRoute() async {
+      final GlobalKey<NavigatorState> nav = GlobalKey<NavigatorState>();
+      await tester.pumpWidget(
+        MaterialApp(
+          navigatorKey: nav,
+          home: const Scaffold(
+            body: Text('home'),
+          )
+        )
+      );
+
+      nav.currentState!.push(MaterialPageRoute<void>(builder: (_) => const Placeholder())); // This should create a route
+      await tester.pumpAndSettle();
+
+      nav.currentState!.pop();
+      await tester.pumpAndSettle(); // this should dispose the route.
+    }
+
+    final List<ObjectEvent> events = <ObjectEvent>[];
+    void listener(ObjectEvent event) {
+      if (event.object.runtimeType == MaterialPageRoute<void>) {
+        events.add(event);
+      }
+    }
+    MemoryAllocations.instance.addListener(listener);
+
+    await createAndDisposeRoute();
+    expect(events, hasLength(2));
+    expect(events.first, isA<ObjectCreated>());
+    expect(events.last, isA<ObjectDisposed>());
+
+    MemoryAllocations.instance.removeListener(listener);
+  });
+
   testWidgets('Route didAdd and dispose in same frame work', (WidgetTester tester) async {
     // Regression Test for https://github.com/flutter/flutter/issues/61346.
     Widget buildNavigator() {