WindowAudioWorklet should use ContextLifecycleObserver instead of DOMWindowProperty

third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.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/webaudio/WindowAudioWorklet.h"
 
+#include "core/dom/Document.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "modules/webaudio/AudioWorklet.h"
 
 namespace blink {
 
 WindowAudioWorklet::WindowAudioWorklet(LocalDOMWindow& window)
-    : DOMWindowProperty(window.frame()) {}
+    : ContextLifecycleObserver(window.frame()->document()) {}
 
 const char* WindowAudioWorklet::supplementName() {
   return "WindowAudioWorklet";
 }
 
 WindowAudioWorklet& WindowAudioWorklet::from(LocalDOMWindow& window) {
   WindowAudioWorklet* supplement = static_cast<WindowAudioWorklet*>(
       Supplement<LocalDOMWindow>::from(window, supplementName()));
   if (!supplement) {
     supplement = new WindowAudioWorklet(window);
     provideTo(window, supplementName(), supplement);
   }
   return *supplement;
 }
 
 Worklet* WindowAudioWorklet::audioWorklet(DOMWindow& window) {
-  return from(toLocalDOMWindow(window)).audioWorklet();
+  return from(toLocalDOMWindow(window)).audioWorklet(toLocalDOMWindow(window));
 }
 
-AudioWorklet* WindowAudioWorklet::audioWorklet() {
-  if (!m_audioWorklet && frame())
-    m_audioWorklet = AudioWorklet::create(frame());
+AudioWorklet* WindowAudioWorklet::audioWorklet(LocalDOMWindow& window) {
+  if (!m_audioWorklet && getExecutionContext()) {
+    DCHECK(window.frame());
+    m_audioWorklet = AudioWorklet::create(window.frame());
+  }
   return m_audioWorklet.get();
 }
 
-void WindowAudioWorklet::frameDestroyed() {
-  m_audioWorklet.clear();
-  DOMWindowProperty::frameDestroyed();
+// Break the following cycle when the context gets detached.
+// Otherwise, the worklet object will leak.
+//
+// window => window.audioWorklet
+// => WindowAudioWorklet
+// => AudioWorklet  <--- break this reference
+// => ThreadedWorkletMessagingProxy
+// => Document
+// => ... => window
+void WindowAudioWorklet::contextDestroyed() {
+  m_audioWorklet = nullptr;
 }
 
 DEFINE_TRACE(WindowAudioWorklet) {
   visitor->trace(m_audioWorklet);
   Supplement<LocalDOMWindow>::trace(visitor);
-  DOMWindowProperty::trace(visitor);
+  ContextLifecycleObserver::trace(visitor);
 }
 
 }  // namespace blink