MediaSource must use ref-counting to handle pending activity counting.

Source/core/html/HTMLMediaSource.h

 /*
  * 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 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLMediaSource_h
 #define HTMLMediaSource_h
 
 #include "core/html/URLRegistry.h"
+#include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 class WebMediaSource;
 }
 
 namespace WebCore {
 
 class HTMLMediaElement;
 class TimeRanges;
 
-class HTMLMediaSource : public URLRegistrable {
+class HTMLMediaSource : public URLRegistrable, public WillBeGarbageCollectedMixin {
 public:
     static void setRegistry(URLRegistry*);
     static HTMLMediaSource* lookup(const String& url) { return s_registry ? static_cast<HTMLMediaSource*>(s_registry->lookup(url)) : 0; }
 
+#if !ENABLE(OILPAN)
     void ref() { refHTMLMediaSource(); }
     void deref() { derefHTMLMediaSource(); }
+#endif
 
     // Called when an HTMLMediaElement is attempting to attach to this object,
     // and helps enforce attachment to at most one element at a time.
     // If already attached, returns false. Otherwise, must be in
     // 'closed' state, and returns true to indicate attachment success.
     // Reattachment allowed by first calling close() (even if already in 'closed').
     // Once attached, the source uses the element to synchronously service some
     // API operations like duration change that may need to initiate seek.
     virtual bool attachToElement(HTMLMediaElement*) = 0;
     virtual void setWebMediaSourceAndOpen(PassOwnPtr<blink::WebMediaSource>) = 0;
     virtual void close() = 0;
     virtual bool isClosed() const = 0;
     virtual double duration() const = 0;
     virtual PassRefPtr<TimeRanges> buffered() const = 0;
+#if !ENABLE(OILPAN)
     virtual void refHTMLMediaSource() = 0;
     virtual void derefHTMLMediaSource() = 0;
+#endif
 
     // URLRegistrable
     virtual URLRegistry& registry() const OVERRIDE { return *s_registry; }
 
+    virtual void trace(Visitor*) { }
+
 private:
     static URLRegistry* s_registry;
 };
 
 }
 
 #endif