WindowAnimationWorklet should use ContextLifecycleObserver instead of DOMWindowProperty

third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/compositorworker/WindowAnimationWorklet.h"
 
+#include "core/dom/Document.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/compositorworker/AnimationWorklet.h"
 
 namespace blink {
 
 WindowAnimationWorklet::WindowAnimationWorklet(LocalDOMWindow& window)
-    : DOMWindowProperty(window.frame()) {}
+    : ContextLifecycleObserver(window.frame()->document()) {}
 
 const char* WindowAnimationWorklet::supplementName() {
   return "WindowAnimationWorklet";
 }
 
 // static
 WindowAnimationWorklet& WindowAnimationWorklet::from(LocalDOMWindow& window) {
   WindowAnimationWorklet* supplement = static_cast<WindowAnimationWorklet*>(
       Supplement<LocalDOMWindow>::from(window, supplementName()));
   if (!supplement) {
     supplement = new WindowAnimationWorklet(window);
     provideTo(window, supplementName(), supplement);
   }
   return *supplement;
 }
 
 // static
 Worklet* WindowAnimationWorklet::animationWorklet(DOMWindow& window) {
-  return from(toLocalDOMWindow(window)).animationWorklet();
+  return from(toLocalDOMWindow(window))
+      .animationWorklet(toLocalDOMWindow(window));
 }
 
-AnimationWorklet* WindowAnimationWorklet::animationWorklet() {
-  if (!m_animationWorklet && frame())
-    m_animationWorklet = AnimationWorklet::create(frame());
+AnimationWorklet* WindowAnimationWorklet::animationWorklet(
+    LocalDOMWindow& window) {
+  if (!m_animationWorklet && getExecutionContext()) {
+    DCHECK(window.frame());
+    m_animationWorklet = AnimationWorklet::create(window.frame());
+  }
   return m_animationWorklet.get();
 }
 
-void WindowAnimationWorklet::frameDestroyed() {
-  m_animationWorklet.clear();
-  DOMWindowProperty::frameDestroyed();
+// Break the following cycle when the context gets detached.
+// Otherwise, the worklet object will leak.
+//
+// window => window.animationWorklet
+// => WindowAnimationWorklet
+// => AnimationWorklet  <--- break this reference
+// => ThreadedWorkletMessagingProxy
+// => Document
+// => ... => window
+void WindowAnimationWorklet::contextDestroyed() {
+  m_animationWorklet = nullptr;
 }
 
 DEFINE_TRACE(WindowAnimationWorklet) {
   visitor->trace(m_animationWorklet);
   Supplement<LocalDOMWindow>::trace(visitor);
-  DOMWindowProperty::trace(visitor);
+  ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink