Remove UntracedMember from WorkerAnimationFrameProvider::offscreen_canvases_

Remove UntracedMember from WorkerAnimationFrameProvider::offscreen_canvases_ and use the safer WeakMember

Bug: 1058341
Change-Id: I62f43a79641eb43fe9c10aedd304e5789760425c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2087871Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758696}

third_party/blink/renderer/core/animation_frame/worker_animation_frame_provider.cc

@@ -71,20 +71,18 @@ void WorkerAnimationFrameProvider::BeginFrame(const viz::BeginFrameArgs& args) {
 
 void WorkerAnimationFrameProvider::RegisterOffscreenCanvas(
     OffscreenCanvas* context) {
-  DCHECK(offscreen_canvases_.Find(context) == kNotFound);
-  offscreen_canvases_.push_back(context);
+  auto result = offscreen_canvases_.insert(context);
+  DCHECK(result.is_new_entry);
 }
 
 void WorkerAnimationFrameProvider::DeregisterOffscreenCanvas(
     OffscreenCanvas* offscreen_canvas) {
-  wtf_size_t pos = offscreen_canvases_.Find(offscreen_canvas);
-  if (pos != kNotFound) {
-    offscreen_canvases_.EraseAt(pos);
-  }
+  offscreen_canvases_.erase(offscreen_canvas);
 }
 
 void WorkerAnimationFrameProvider::Trace(Visitor* visitor) {
   visitor->Trace(callback_collection_);
+  visitor->Trace(offscreen_canvases_);
   visitor->Trace(context_);
 }
 

third_party/blink/renderer/core/animation_frame/worker_animation_frame_provider.h

@@ -51,9 +51,7 @@ class CORE_EXPORT WorkerAnimationFrameProvider
   DISALLOW_COPY_AND_ASSIGN(WorkerAnimationFrameProvider);
   FrameRequestCallbackCollection callback_collection_;
 
-  // To avoid leaking OffscreenCanvas objects, the following vector must
-  // not hold strong references.
-  Vector<UntracedMember<OffscreenCanvas>> offscreen_canvases_;
+  HeapLinkedHashSet<WeakMember<OffscreenCanvas>> offscreen_canvases_;
 
   Member<ExecutionContext> context_;
 

third_party/blink/renderer/core/offscreencanvas/offscreen_canvas.cc

@@ -105,8 +105,6 @@ void OffscreenCanvas::Dispose() {
     context_->DetachHost();
     context_ = nullptr;
   }
-
-  DeregisterFromAnimationFrameProvider();
 }
 
 void OffscreenCanvas::DeregisterFromAnimationFrameProvider() {