WindowAnimationWorklet should use ContextLifecycleObserver instead of DOMWindowProperty

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

Index: third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp
diff --git a/third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp b/third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp
index 3512051bf191613a1f4e16497cccfa9af04b78cf..15a4803470a2130d95c6714f60942b265463d471 100644
--- a/third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp
+++ b/third_party/WebKit/Source/modules/compositorworker/WindowAnimationWorklet.cpp
@@ -4,6 +4,7 @@
 
 #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"
@@ -11,7 +12,7 @@
 namespace blink {
 
 WindowAnimationWorklet::WindowAnimationWorklet(LocalDOMWindow& window)
-    : DOMWindowProperty(window.frame()) {}
+    : ContextLifecycleObserver(window.frame()->document()) {}
 
 const char* WindowAnimationWorklet::supplementName() {
   return "WindowAnimationWorklet";
@@ -30,24 +31,36 @@ WindowAnimationWorklet& WindowAnimationWorklet::from(LocalDOMWindow& window) {
 
 // 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