Media Controls: do not use events but C++ callbacks for insertion/removal from document.

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 26 matching lines @@
 class MediaControlsOrientationLockDelegate;
 class MediaControlsWindowEventListener;
 class ShadowRoot;
 
 class CORE_EXPORT MediaControls final : public HTMLDivElement {
  public:
   static MediaControls* create(HTMLMediaElement&, ShadowRoot&);
 
   HTMLMediaElement& mediaElement() const { return *m_mediaElement; }
 
+  // Node override.
+  Node::InsertionNotificationRequest insertedInto(ContainerNode*) override;
+  void removedFrom(ContainerNode*) override;
+
   void reset();
 
   void show();
   void hide();
   bool isVisible() const;
 
   void beginScrubbing();
   void endScrubbing();
 
   void updateCurrentTimeDisplay();
@@ skipping 102 matching lines @@
   // do fit.  This requires that m_panelWidth is current.
   void computeWhichControlsFit();
 
   // Node
   bool isMediaControls() const override { return true; }
   bool willRespondToMouseMoveEvents() override { return true; }
   void defaultEventHandler(Event*) override;
   bool containsRelatedTarget(Event*);
 
   // Methods called by MediaControlsMediaEventListener.
-  void onInsertedIntoDocument();
-  void onRemovedFromDocument();
   void onVolumeChange();
   void onFocusIn();
   void onTimeUpdate();
   void onDurationChange();
   void onPlay();
   void onPause();
   void onTextTracksAddedOrRemoved();
   void onTextTracksChanged();
   void onError();
   void onLoadedMetadata();
@@ skipping 42 matching lines @@
   int m_panelWidth;
 
   bool m_keepShowingUntilTimerFires : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }  // namespace blink
 
 #endif