Oilpan: handle MediaControls like the GCed object it is.

Source/core/html/shadow/MediaControlElementTypes.cpp

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 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.
@@ skipping 50 matching lines @@
 MediaControlElementType mediaControlElementType(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(node->isMediaControlElement());
     HTMLElement* element = toHTMLElement(node);
     if (isHTMLInputElement(*element))
         return static_cast<MediaControlInputElement*>(element)->displayType();
     return static_cast<MediaControlDivElement*>(element)->displayType();
 }
 
 MediaControlElement::MediaControlElement(MediaControls& mediaControls, MediaControlElementType displayType, HTMLElement* element)
-    : m_mediaControls(mediaControls)
+    : m_mediaControls(&mediaControls)
     , m_displayType(displayType)
     , m_element(element)
     , m_isWanted(true)
     , m_doesFit(true)
 {
 }
 
 HTMLMediaElement& MediaControlElement::mediaElement() const
 {
     return mediaControls().mediaElement();
@@ skipping 29 matching lines @@
     if (displayType == m_displayType)
         return;
 
     m_displayType = displayType;
     if (LayoutObject* object = m_element->layoutObject())
         object->setShouldDoFullPaintInvalidation();
 }
 
 DEFINE_TRACE(MediaControlElement)
 {
+    visitor->trace(m_mediaControls);
     visitor->trace(m_element);
 }
 
 // ----------------------------
 
 MediaControlDivElement::MediaControlDivElement(MediaControls& mediaControls, MediaControlElementType displayType)
     : HTMLDivElement(mediaControls.document())
     , MediaControlElement(mediaControls, displayType, this)
 {
 }
@@ skipping 30 matching lines @@
     , m_currentValue(0)
 {
 }
 
 void MediaControlTimeDisplayElement::setCurrentValue(double time)
 {
     m_currentValue = time;
 }
 
 } // namespace blink