From 0cc7db54ce5cd07c7dd91a2b64e6a8ad85f45cf7 Mon Sep 17 00:00:00 2001
From: Dan Field <dnfield@google.com>
Date: Thu, 28 Jul 2022 11:36:04 -0700
Subject: [PATCH] Guard against usage after async callbacks in
 RenderAndroidView, unregister listener (#108496)

---
 .../lib/src/rendering/platform_view.dart      |  9 +++++
 .../test/rendering/platform_view_test.dart    | 39 +++++++++++++++++++
 .../test/services/fake_platform_views.dart    |  4 +-
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/packages/flutter/lib/src/rendering/platform_view.dart b/packages/flutter/lib/src/rendering/platform_view.dart
index faa846c7d94..5ab23e1c867 100644
--- a/packages/flutter/lib/src/rendering/platform_view.dart
+++ b/packages/flutter/lib/src/rendering/platform_view.dart
@@ -109,6 +109,7 @@ class RenderAndroidView extends PlatformViewRenderBox {
   /// Sets a new Android view controller.
   @override
   set controller(AndroidViewController controller) {
+    assert(!_isDisposed);
     assert(_viewController != null);
     assert(controller != null);
     if (_viewController == controller) {
@@ -140,6 +141,7 @@ class RenderAndroidView extends PlatformViewRenderBox {
   }
 
   void _onPlatformViewCreated(int id) {
+    assert(!_isDisposed);
     markNeedsSemanticsUpdate();
   }
 
@@ -179,8 +181,14 @@ class RenderAndroidView extends PlatformViewRenderBox {
       targetSize = size;
       if (_viewController.isCreated) {
         _currentTextureSize = await _viewController.setSize(targetSize);
+        if (_isDisposed) {
+          return;
+        }
       } else {
         await _viewController.create(size: targetSize);
+        if (_isDisposed) {
+          return;
+        }
         _currentTextureSize = targetSize;
       }
       // We've resized the platform view to targetSize, but it is possible that
@@ -248,6 +256,7 @@ class RenderAndroidView extends PlatformViewRenderBox {
   void dispose() {
     _isDisposed = true;
     _clipRectLayer.layer = null;
+    _viewController.removeOnPlatformViewCreatedListener(_onPlatformViewCreated);
     super.dispose();
   }
 
diff --git a/packages/flutter/test/rendering/platform_view_test.dart b/packages/flutter/test/rendering/platform_view_test.dart
index 9ede358bd2d..9f3d2b26bd6 100644
--- a/packages/flutter/test/rendering/platform_view_test.dart
+++ b/packages/flutter/test/rendering/platform_view_test.dart
@@ -221,6 +221,45 @@ void main() {
       expect(renderBox.debugLayer!.firstChild, isA<TextureLayer>());
     });
   });
+
+  test('markNeedsPaint does not get called on a disposed RO', () async {
+    FakeAsync().run((FakeAsync async) {
+      final AndroidViewController viewController =
+        PlatformViewsService.initAndroidView(id: 0, viewType: 'webview', layoutDirection: TextDirection.rtl);
+      final RenderAndroidView renderBox = RenderAndroidView(
+        viewController: viewController,
+        hitTestBehavior: PlatformViewHitTestBehavior.opaque,
+        gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{},
+      );
+
+      final Completer<void> viewCreation = Completer<void>();
+      const MethodChannel channel = MethodChannel('flutter/platform_views');
+      binding.defaultBinaryMessenger.setMockMethodCallHandler(channel, (MethodCall methodCall) async {
+        assert(methodCall.method == 'create', 'Unexpected method call');
+        await viewCreation.future;
+        return /*textureId=*/ 0;
+      });
+
+      layout(renderBox);
+      pumpFrame(phase: EnginePhase.paint);
+
+      expect(renderBox.debugLayer, isNotNull);
+      expect(renderBox.debugLayer!.hasChildren, isFalse);
+      expect(viewController.isCreated, isFalse);
+      expect(renderBox.debugNeedsPaint, isFalse);
+
+      renderBox.dispose();
+      viewCreation.complete();
+      async.flushMicrotasks();
+
+      expect(viewController.isCreated, isTrue);
+      expect(renderBox.debugNeedsPaint, isFalse);
+      expect(renderBox.debugLayer, isNull);
+
+      pumpFrame(phase: EnginePhase.paint);
+      expect(renderBox.debugLayer, isNull);
+    });
+  });
 }
 
 ui.PointerData _pointerData(
diff --git a/packages/flutter/test/services/fake_platform_views.dart b/packages/flutter/test/services/fake_platform_views.dart
index 95d9c7e2678..d5ebe534c16 100644
--- a/packages/flutter/test/services/fake_platform_views.dart
+++ b/packages/flutter/test/services/fake_platform_views.dart
@@ -101,9 +101,7 @@ class FakeAndroidViewController implements AndroidViewController {
   }
 
   @override
-  void removeOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {
-    throw UnimplementedError();
-  }
+  void removeOnPlatformViewCreatedListener(PlatformViewCreatedCallback listener) {}
 
   @override
   Future<void> sendMotionEvent(AndroidMotionEvent event) {