Media: fix memory leak because of the document holding on an EventListener.

third_party/WebKit/Source/core/html/shadow/MediaControls.h

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 23 matching lines @@
 
 class Event;
 class MediaControlsMediaEventListener;
 class MediaControlsOrientationLockDelegate;
 class MediaControlsWindowEventListener;
 class ShadowRoot;
 
 class CORE_EXPORT MediaControls final : public HTMLDivElement {
  public:
   static MediaControls* create(HTMLMediaElement&, ShadowRoot&);
+  ~MediaControls() override;
 
   HTMLMediaElement& mediaElement() const { return *m_mediaElement; }
 
   void reset();
 
+  // Called when the HTMLMediaElement is no longer in the document to the
+  // MediaControls instance can be ready to be garbage collected by removing
+  // event listeners.
+  void detach();
+
   void show();
   void hide();
   bool isVisible() const;
 
   void beginScrubbing();
   void endScrubbing();
 
   void updateCurrentTimeDisplay();
 
   void toggleTextTrackList();
@@ skipping 162 matching lines @@
   int m_panelWidth;
 
   bool m_keepShowingUntilTimerFires : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }  // namespace blink
 
 #endif