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

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.h
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.h b/third_party/WebKit/Source/core/html/shadow/MediaControls.h
index c38bf9d2274e3308cb2635cf7166eb671f2ac280..5ced7c1bb568479c6d9a85fa667a07c99240e780 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.h
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.h
@@ -44,6 +44,10 @@ class CORE_EXPORT MediaControls final : public HTMLDivElement {
 
   HTMLMediaElement& mediaElement() const { return *m_mediaElement; }
 
+  // Node override.
+  Node::InsertionNotificationRequest insertedInto(ContainerNode*) override;
+  void removedFrom(ContainerNode*) override;
+
   void reset();
 
   void show();
@@ -166,8 +170,6 @@ class CORE_EXPORT MediaControls final : public HTMLDivElement {
   bool containsRelatedTarget(Event*);
 
   // Methods called by MediaControlsMediaEventListener.
-  void onInsertedIntoDocument();
-  void onRemovedFromDocument();
   void onVolumeChange();
   void onFocusIn();
   void onTimeUpdate();