Oilpan: have MediaController weakly refer to its media elements.

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 307 matching lines @@
     // destructed ActiveDOMObject::executionContext() returns 0.
     if (ActiveDOMObject::executionContext())
         setShouldDelayLoadEvent(false);
 #else
     setShouldDelayLoadEvent(false);
 #endif
 
 #if !ENABLE(OILPAN)
     if (m_textTracks)
         m_textTracks->clearOwner();
-#endif
 
     if (m_mediaController) {
         m_mediaController->removeMediaElement(this);
         m_mediaController = nullptr;
     }
+#endif
 
     closeMediaSource();
 
 #if !ENABLE(OILPAN)
     removeElementFromDocumentMap(this, &document());
 #endif
 
     // Destroying the player may cause a resource load to be canceled,
     // which could result in userCancelledLoad() being called back.
     // Setting m_completelyLoaded ensures that such a call will not cause
@@ skipping 3162 matching lines @@
 
     // Otherwise, let controller be a newly created MediaController.
     setControllerInternal(MediaController::create(Node::executionContext()));
 }
 
 MediaController* HTMLMediaElement::controller() const
 {
     return m_mediaController.get();
 }
 
-void HTMLMediaElement::setController(PassRefPtr<MediaController> controller)
+void HTMLMediaElement::setController(PassRefPtrWillBeRawPtr<MediaController> controller)
 {
     // 4.8.10.11.2 Media controllers: controller attribute.
     // On setting, it must first remove the element's mediagroup attribute, if any,
     removeAttribute(mediagroupAttr);
     // and then set the current media controller to the given value.
     setControllerInternal(controller);
 }
 
-void HTMLMediaElement::setControllerInternal(PassRefPtr<MediaController> controller)
+void HTMLMediaElement::setControllerInternal(PassRefPtrWillBeRawPtr<MediaController> controller)
 {
     if (m_mediaController)
         m_mediaController->removeMediaElement(this);
 
     m_mediaController = controller;
 
     if (m_mediaController)
         m_mediaController->addMediaElement(this);
 }
 
@@ skipping 114 matching lines @@
     HTMLElement::defaultEventHandler(event);
 }
 
 void HTMLMediaElement::trace(Visitor* visitor)
 {
     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);
 }
 
 }