Oilpan: have media element prefinalizer handle all finalization.

Source/modules/mediasource/MediaSource.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 245 matching lines @@
 const AtomicString& MediaSource::interfaceName() const
 {
     return EventTargetNames::MediaSource;
 }
 
 ExecutionContext* MediaSource::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
-void MediaSource::clearWeakMembers(Visitor* visitor)
-{
-#if ENABLE(OILPAN)
-    // Oilpan: If the MediaSource survived, but its attached media
-    // element did not, signal the element that it can safely
-    // notify its MediaSource during finalization by calling close().
-    if (m_attachedElement && !Heap::isHeapObjectAlive(m_attachedElement)) {
-        m_attachedElement->setCloseMediaSourceWhenFinalizing();
-        m_attachedElement.clear();
-    }
-#endif
-}
-
 DEFINE_TRACE(MediaSource)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_asyncEventQueue);
 #endif
+    visitor->trace(m_attachedElement);
     visitor->trace(m_sourceBuffers);
     visitor->trace(m_activeSourceBuffers);
-    visitor->template registerWeakMembers<MediaSource, &MediaSource::clearWeakMembers>(this);
     RefCountedGarbageCollectedEventTargetWithInlineData<MediaSource>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 void MediaSource::setWebMediaSourceAndOpen(PassOwnPtr<WebMediaSource> webMediaSource)
 {
     TRACE_EVENT_ASYNC_END0("media", "MediaSource::attachToElement", this);
     ASSERT(webMediaSource);
     ASSERT(!m_webMediaSource);
     ASSERT(m_attachedElement);
@@ skipping 316 matching lines @@
 
     m_asyncEventQueue->enqueueEvent(event.release());
 }
 
 URLRegistry& MediaSource::registry() const
 {
     return MediaSourceRegistry::registry();
 }
 
 } // namespace blink