Let AutoplayUmaHelper listen to visibilitychange instead of unload

third_party/WebKit/Source/core/html/AutoplayUmaHelper.h

Index: third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
diff --git a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
index 7dda64bb56d55bc2b799c5290a8a9b9f2c420e88..706dd56183f0ea03aad7098bc37ec2557184ecfc 100644
--- a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.h
@@ -5,6 +5,8 @@
 #ifndef AutoplayUmaHelper_h
 #define AutoplayUmaHelper_h
 
+#include "core/CoreExport.h"
+#include "core/dom/ContextLifecycleObserver.h"
 #include "core/events/EventListener.h"
 #include "platform/heap/Handle.h"
 
@@ -40,7 +42,10 @@ class Document;
 class ElementVisibilityObserver;
 class HTMLMediaElement;
 
-class AutoplayUmaHelper final : public EventListener {
+class CORE_EXPORT AutoplayUmaHelper : public EventListener,
+                                      public ContextLifecycleObserver {
+  USING_GARBAGE_COLLECTED_MIXIN(AutoplayUmaHelper);
+
  public:
   static AutoplayUmaHelper* create(HTMLMediaElement*);
 
@@ -48,6 +53,8 @@ class AutoplayUmaHelper final : public EventListener {
 
   bool operator==(const EventListener&) const override;
 
+  void contextDestroyed() override;
+
   void onAutoplayInitiated(AutoplaySource);
 
   void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
@@ -61,15 +68,15 @@ class AutoplayUmaHelper final : public EventListener {
   DECLARE_VIRTUAL_TRACE();
 
  private:
-  explicit AutoplayUmaHelper(HTMLMediaElement*);
+  friend class MockAutoplayUmaHelper;
 
+  explicit AutoplayUmaHelper(HTMLMediaElement*);
   void handleEvent(ExecutionContext*, Event*) override;
-
   void handlePlayingEvent();
   void handlePauseEvent();
-  void handleUnloadEvent();
+  virtual void handleContextDestroyed();  // Make virtual for testing.
 
-  void maybeUnregisterUnloadListener();
+  void maybeUnregisterContextDestroyedObserver();
 
   void maybeStartRecordingMutedVideoPlayMethodBecomeVisible();
   void maybeStopRecordingMutedVideoPlayMethodBecomeVisible(bool isVisible);
@@ -80,7 +87,7 @@ class AutoplayUmaHelper final : public EventListener {
   void onVisibilityChangedForMutedVideoOffscreenDuration(bool isVisibile);
   void onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible);
 
-  bool shouldListenToUnloadEvent() const;
+  bool shouldListenToContextDestroyed() const;
 
   // The autoplay source. Use AutoplaySource::NumberOfSources for invalid
   // source.