Let AutoplayUmaHelper listen to visibilitychange instead of unload

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

 // 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.
 
 #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"
 
 namespace blink {
 
 // These values are used for histograms. Do not reorder.
 enum class AutoplaySource {
   // Autoplay comes from HTMLMediaElement `autoplay` attribute.
   Attribute = 0,
   // Autoplay comes from `play()` method.
@@ skipping 15 matching lines @@
   AutoplayBlockedReasonSetting = 1,
   AutoplayBlockedReasonDataSaverAndSetting = 2,
   // Keey at the end.
   AutoplayBlockedReasonMax = 3
 };
 
 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*);
 
   ~AutoplayUmaHelper();
 
   bool operator==(const EventListener&) const override;
 
+  void contextDestroyed() override;
+
   void onAutoplayInitiated(AutoplaySource);
 
   void recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus);
 
   void didMoveToNewDocument(Document& oldDocument);
 
   bool isVisible() const { return m_isVisible; }
 
   bool hasSource() const { return m_source != AutoplaySource::NumberOfSources; }
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
+  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);
 
   void maybeStartRecordingMutedVideoOffscreenDuration();
   void maybeStopRecordingMutedVideoOffscreenDuration();
 
   void onVisibilityChangedForMutedVideoOffscreenDuration(bool isVisibile);
   void onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible);
 
-  bool shouldListenToUnloadEvent() const;
+  bool shouldListenToContextDestroyed() const;
 
   // The autoplay source. Use AutoplaySource::NumberOfSources for invalid
   // source.
   AutoplaySource m_source;
   // The media element this UMA helper is attached to. |m_element| owns |this|.
   Member<HTMLMediaElement> m_element;
 
   // The observer is used to observe whether a muted video autoplaying by play()
   // method become visible at some point.
   // The UMA is pending for recording as long as this observer is non-null.
@@ skipping 17 matching lines @@
   // The observer is used to observer an autoplaying muted video changing it's
   // visibility, which is used for offscreen duration UMA.  The UMA is pending
   // for recording as long as this observer is non-null.
   Member<ElementVisibilityObserver>
       m_mutedVideoOffscreenDurationVisibilityObserver;
 };
 
 }  // namespace blink
 
 #endif  // AutoplayUmaHelper_h