Revert "FocusNode and FocusManager should dispatch creation in constructor." (#133474)

Reverts flutter/flutter#133352

Tree is failing on Mac and Linux customer_testing on this PR.
https://ci.chromium.org/ui/p/flutter/builders/prod/Mac%20customer_testing/14646/overview
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20customer_testing/14974/overview

packages/flutter/lib/src/material/drawer.dart

@@ -471,7 +471,6 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
   void dispose() {
     _historyEntry?.remove();
     _controller.dispose();
-    _focusScopeNode.dispose();
     super.dispose();
   }
 

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

@@ -437,10 +437,6 @@ class FocusNode with DiagnosticableTreeMixin, ChangeNotifier {
         _descendantsAreTraversable = descendantsAreTraversable {
     // Set it via the setter so that it does nothing on release builds.
     this.debugLabel = debugLabel;
-
-    if (kFlutterMemoryAllocationsEnabled) {
-      maybeDispatchObjectCreation();
-    }
   }
 
   /// If true, tells the focus traversal policy to skip over this node for
@@ -1467,9 +1463,6 @@ class FocusManager with DiagnosticableTreeMixin, ChangeNotifier {
   /// handlers, callers must call [registerGlobalHandlers]. See the
   /// documentation in that method for caveats to watch out for.
   FocusManager() {
-    if (kFlutterMemoryAllocationsEnabled) {
-      maybeDispatchObjectCreation();
-    }
     rootScope._manager = this;
   }
 

packages/flutter/test/widgets/focus_manager_test.dart

@@ -1609,41 +1609,6 @@ void main() {
     tester.binding.focusManager.removeListener(handleFocusChange);
   });
 
-  test('$FocusManager dispatches object creation in constructor', () {
-    final List<ObjectEvent> events = <ObjectEvent>[];
-    void listener(ObjectEvent event) {
-      if (event.object.runtimeType == FocusManager) {
-        events.add(event);
-      }
-    }
-    MemoryAllocations.instance.addListener(listener);
-
-    final FocusManager focusManager = FocusManager();
-
-    expect(events, hasLength(1));
-
-    focusManager.dispose();
-
-    MemoryAllocations.instance.removeListener(listener);
-  });
-
-  test('$FocusNode dispatches object creation in constructor', () {
-    final List<ObjectEvent> events = <ObjectEvent>[];
-    void listener(ObjectEvent event) {
-      if (event.object.runtimeType == FocusNode) {
-        events.add(event);
-      }
-    }
-    MemoryAllocations.instance.addListener(listener);
-
-    final FocusNode focusManager = FocusNode();
-
-    expect(events, hasLength(1));
-
-    focusManager.dispose();
-    MemoryAllocations.instance.removeListener(listener);
-  });
-
   testWidgets('FocusManager notifies listeners when a widget loses focus because it was removed.', (WidgetTester tester) async {
     final FocusNode nodeA = FocusNode(debugLabel: 'a');
     final FocusNode nodeB = FocusNode(debugLabel: 'b');

packages/flutter/test/widgets/memory_allocations_test.dart

@@ -6,26 +6,20 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-    int _creations = 0;
-    int _disposals = 0;
-
 void main() {
   final MemoryAllocations ma = MemoryAllocations.instance;
 
+  setUp(() {
+    assert(!ma.hasListeners);
+  });
+
   test('Publishers dispatch events in debug mode', () async {
-    void listener(ObjectEvent event) {
-      if (event is ObjectDisposed) {
-        _disposals++;
-      }
-      if (event is ObjectCreated) {
-        _creations++;
-      }
-    }
+    int eventCount = 0;
+    void listener(ObjectEvent event) => eventCount++;
     ma.addListener(listener);
 
-    final _EventStats actual = await _activateFlutterObjectsAndReturnCountOfEvents();
-    expect(actual.creations, _creations);
-    expect(actual.disposals, _disposals);
+    final int expectedEventCount = await _activateFlutterObjectsAndReturnCountOfEvents();
+    expect(eventCount, expectedEventCount);
 
     ma.removeListener(listener);
     expect(ma.hasListeners, isFalse);
@@ -35,8 +29,6 @@ void main() {
     bool stateCreated = false;
     bool stateDisposed = false;
 
-    expect(ma.hasListeners, false);
-
     void listener(ObjectEvent event) {
       if (event is ObjectCreated && event.object is State) {
         stateCreated = true;
@@ -55,7 +47,7 @@ void main() {
     expect(stateCreated, isTrue);
     expect(stateDisposed, isTrue);
     ma.removeListener(listener);
-    expect(ma.hasListeners, false);
+    expect(ma.hasListeners, isFalse);
   });
 }
 
@@ -70,8 +62,7 @@ class _TestElement extends RenderObjectElement with RootElementMixin {
   _TestElement(): super(_TestLeafRenderObjectWidget());
 
   void makeInactive() {
-    final FocusManager newFocusManager = FocusManager();
-    assignOwner(BuildOwner(focusManager: newFocusManager));
+    assignOwner(BuildOwner(focusManager: FocusManager()));
     mount(null, null);
     deactivate();
   }
@@ -118,22 +109,15 @@ class _TestStatefulWidgetState extends State<_TestStatefulWidget> {
   }
 }
 
-
-class _EventStats {
-  int creations = 0;
-  int disposals = 0;
-}
-
 /// Create and dispose Flutter objects to fire memory allocation events.
-Future<_EventStats> _activateFlutterObjectsAndReturnCountOfEvents() async {
-  final _EventStats result = _EventStats();
+Future<int> _activateFlutterObjectsAndReturnCountOfEvents() async {
+  int count = 0;
 
-  final _TestElement element = _TestElement(); result.creations++;
-  final RenderObject renderObject = _TestRenderObject(); result.creations++;
+  final _TestElement element = _TestElement(); count++;
+  final RenderObject renderObject = _TestRenderObject(); count++;
 
-  element.makeInactive(); result.creations += 3; // 1 for the new BuildOwner, 1 for the new FocusManager, 1 for the new FocusScopeNode
-  element.unmount(); result.disposals += 2; // 1 for the old BuildOwner, 1 for the element
-  renderObject.dispose(); result.disposals += 1;
+  element.makeInactive(); element.unmount(); count += 3;
+  renderObject.dispose(); count++;
 
-  return result;
+  return count;
 }