Oilpan: Prepare to move EventQueue and its subclasses to Oilpan heap.

Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 285 matching lines @@
         m_userGestureRequiredForPlay = true;
 
     setHasCustomStyleCallbacks();
     addElementToDocumentMap(this, &document);
 }
 
 HTMLMediaElement::~HTMLMediaElement()
 {
     WTF_LOG(Media, "HTMLMediaElement::~HTMLMediaElement");
 
-    m_asyncEventQueue->close();
-
 #if ENABLE(OILPAN)
     // If the HTMLMediaElement dies with the document we are not
     // allowed to touch the document to adjust delay load event counts
     // because the document could have been already
     // destructed. However, if the HTMLMediaElement dies with the
     // document there is no need to change the delayed load counts
     // because no load event will fire anyway. If the document is
     // still alive we do have to decrement the load delay counts. We
     // determine if the document is alive via the ActiveDOMObject
     // which is a context lifecycle observer. If the Document has been
     // destructed ActiveDOMObject::executionContext() returns 0.
     if (ActiveDOMObject::executionContext())
         setShouldDelayLoadEvent(false);
 #else
+    // HTMLMediaElement and m_asyncEventQueue always become unreachable
+    // together. So HTMLMediaElemenet and m_asyncEventQueue are destructed in
+    // the same GC. We don't need to close it explicitly in Oilpan.
+    m_asyncEventQueue->close();
+
     setShouldDelayLoadEvent(false);
-#endif
 
-#if !ENABLE(OILPAN)
     if (m_textTracks)
         m_textTracks->clearOwner();
 
     if (m_mediaController) {
         m_mediaController->removeMediaElement(this);
         m_mediaController = nullptr;
     }
 #endif
 
     closeMediaSource();
@@ skipping 3308 matching lines @@
 {
     if (event->type() == EventTypeNames::focusin) {
         if (hasMediaControls())
             mediaControls()->mediaElementFocused();
     }
     HTMLElement::defaultEventHandler(event);
 }
 
 void HTMLMediaElement::trace(Visitor* visitor)
 {
+    visitor->trace(m_asyncEventQueue);
     visitor->trace(m_error);
     visitor->trace(m_currentSourceNode);
     visitor->trace(m_nextChildNodeToConsider);
     visitor->trace(m_textTracks);
     visitor->trace(m_textTracksWhenResourceSelectionBegan);
     visitor->trace(m_mediaController);
     WillBeHeapSupplementable<HTMLMediaElement>::trace(visitor);
     HTMLElement::trace(visitor);
 }
 
 }