Fix performance regression. (#111615)

packages/flutter/lib/src/foundation/change_notifier.dart

@@ -215,13 +215,11 @@ class ChangeNotifier implements Listenable {
   void addListener(VoidCallback listener) {
     assert(ChangeNotifier.debugAssertNotDisposed(this));
     if (kFlutterMemoryAllocationsEnabled && !_creationDispatched) {
-      MemoryAllocations.instance.dispatchObjectEvent(() {
-        return ObjectCreated(
-          library: _flutterFoundationLibrary,
-          className: 'ChangeNotifier',
-          object: this,
-        );
-      });
+      MemoryAllocations.instance.dispatchObjectEvent(ObjectCreated(
+        library: _flutterFoundationLibrary,
+        className: 'ChangeNotifier',
+        object: this,
+      ));
       _creationDispatched = true;
     }
     if (_count == _listeners.length) {
@@ -328,7 +326,7 @@ class ChangeNotifier implements Listenable {
       return true;
     }());
     if (kFlutterMemoryAllocationsEnabled && _creationDispatched) {
-      MemoryAllocations.instance.dispatchObjectEvent(() => ObjectDisposed(object: this));
+      MemoryAllocations.instance.dispatchObjectEvent(ObjectDisposed(object: this));
     }
     _listeners = _emptyListeners;
     _count = 0;
@@ -466,13 +464,11 @@ class ValueNotifier<T> extends ChangeNotifier implements ValueListenable<T> {
   /// Creates a [ChangeNotifier] that wraps this value.
   ValueNotifier(this._value) {
     if (kFlutterMemoryAllocationsEnabled) {
-      MemoryAllocations.instance.dispatchObjectEvent(() {
-        return ObjectCreated(
-          library: _flutterFoundationLibrary,
-          className: 'ValueNotifier',
-          object: this,
-        );
-      });
+      MemoryAllocations.instance.dispatchObjectEvent(ObjectCreated(
+        library: _flutterFoundationLibrary,
+        className: 'ValueNotifier',
+        object: this,
+      ));
     }
     _creationDispatched = true;
   }

packages/flutter/lib/src/foundation/memory_allocations.dart

@@ -12,11 +12,11 @@ const bool _kMemoryAllocations = bool.fromEnvironment('flutter.memory_allocation
 
 /// If true, Flutter objects dispatch the memory allocation events.
 ///
-/// By default, the constant is true for profile and debug mode and false
-/// for release mode, for app size optimization goals.
+/// By default, the constant is true for debug mode and false
+/// for profile and release modes.
 /// To enable the dispatching for release mode, pass the compilation flag
 /// `--dart-define=flutter.memory_allocations=true`.
-const bool kFlutterMemoryAllocationsEnabled = _kMemoryAllocations || kProfileMode || kDebugMode;
+const bool kFlutterMemoryAllocationsEnabled = _kMemoryAllocations || kDebugMode;
 
 const String _dartUiLibrary = 'dart:ui';
 
@@ -54,9 +54,6 @@ abstract class ObjectEvent{
 /// A listener of [ObjectEvent].
 typedef ObjectEventListener = void Function(ObjectEvent);
 
-/// A builder of [ObjectEvent].
-typedef ObjectEventBuilder = ObjectEvent Function();
-
 /// An event that describes creation of an object.
 class ObjectCreated extends ObjectEvent {
   /// Creates an instance of [ObjectCreated].
@@ -225,7 +222,7 @@ class MemoryAllocations {
   /// after the removal.
   ///
   /// Only call this when [kFlutterMemoryAllocationsEnabled] is true.
-  void dispatchObjectEvent(ObjectEventBuilder objectEventBuilder) {
+  void dispatchObjectEvent(ObjectEvent event) {
     if (!kFlutterMemoryAllocationsEnabled) {
       return;
     }
@@ -234,7 +231,6 @@ class MemoryAllocations {
       return;
     }
 
-    final ObjectEvent event = objectEventBuilder();
     _activeDispatchLoops++;
     final int end = listeners.length;
     for (int i = 0; i < end; i++) {
@@ -285,38 +281,30 @@ class MemoryAllocations {
   }
 
   void _imageOnCreate(ui.Image image) {
-    dispatchObjectEvent(() {
-      return ObjectCreated(
-        library: _dartUiLibrary,
-        className: 'Image',
-        object: image,
-      );
-    });
+    dispatchObjectEvent(ObjectCreated(
+      library: _dartUiLibrary,
+      className: 'Image',
+      object: image,
+    ));
   }
 
   void _pictureOnCreate(ui.Picture picture) {
-    dispatchObjectEvent(() {
-      return ObjectCreated(
-        library: _dartUiLibrary,
-        className: 'Picture',
-        object: picture,
-      );
-    });
+    dispatchObjectEvent(ObjectCreated(
+      library: _dartUiLibrary,
+      className: 'Picture',
+      object: picture,
+    ));
   }
 
   void _imageOnDispose(ui.Image image) {
-    dispatchObjectEvent(() {
-      return ObjectDisposed(
-        object: image,
-      );
-    });
+    dispatchObjectEvent(ObjectDisposed(
+      object: image,
+    ));
   }
 
   void _pictureOnDispose(ui.Picture picture) {
-    dispatchObjectEvent(() {
-      return ObjectDisposed(
-        object: picture,
-      );
-    });
+    dispatchObjectEvent(ObjectDisposed(
+      object: picture,
+    ));
   }
 }

packages/flutter/test/foundation/memory_allocations_test.dart

@@ -24,13 +24,13 @@ void main() {
 
     ma.addListener(listener);
     _checkSdkHandlersSet();
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(recievedEvent, equals(event));
     expect(ma.hasListeners, isTrue);
     recievedEvent = null;
 
     ma.removeListener(listener);
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(recievedEvent, isNull);
     expect(ma.hasListeners, isFalse);
     _checkSdkHandlersNotSet();
@@ -56,7 +56,7 @@ void main() {
     ma.addListener(badListener2);
     ma.addListener(listener2);
 
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>['badListener1', 'listener1', 'badListener2','listener2']);
     expect(tester.takeException(), contains('Multiple exceptions (2)'));
 
@@ -69,7 +69,7 @@ void main() {
 
     log.clear();
     expect(ma.hasListeners, isFalse);
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>[]);
   });
 
@@ -86,11 +86,11 @@ void main() {
     ma.addListener(listener1);
     _checkSdkHandlersSet();
 
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>['listener1']);
     log.clear();
 
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>['listener1','listener2']);
     log.clear();
 
@@ -99,7 +99,7 @@ void main() {
     _checkSdkHandlersNotSet();
 
     expect(ma.hasListeners, isFalse);
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>[]);
   });
 
@@ -117,7 +117,7 @@ void main() {
     ma.addListener(listener1);
     ma.addListener(listener2);
 
-    ma.dispatchObjectEvent(() => event);
+    ma.dispatchObjectEvent(event);
     expect(log, <String>['listener1']);
     log.clear();