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

Source/modules/mediasource/MediaSource.h

Index: Source/modules/mediasource/MediaSource.h
diff --git a/Source/modules/mediasource/MediaSource.h b/Source/modules/mediasource/MediaSource.h
index 8c95f7c091b45c49d80d3e6f329dd783981f2e74..a0f09de5e1076efa51b971969ddecd851264df16 100644
--- a/Source/modules/mediasource/MediaSource.h
+++ b/Source/modules/mediasource/MediaSource.h
@@ -51,13 +51,15 @@ namespace WebCore {
 class ExceptionState;
 class GenericEventQueue;
 
+// FIXME: Oilpan: Change this to RefCountedGarbageCollectedWillBeGarbageCollectedFinalized
+// if MediaSource stops using ActiveDOMObject::setPendingActivity.
 class MediaSource FINAL
-    : public RefCountedGarbageCollectedWillBeGarbageCollectedFinalized<MediaSource>
+    : public RefCountedGarbageCollected<MediaSource>
     , public HTMLMediaSource
     , public ActiveDOMObject
     , public EventTargetWithInlineData
     , public ScriptWrappable {
-    DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED(RefCountedGarbageCollected<MediaSource>);
+    DEFINE_EVENT_TARGET_REFCOUNTING(RefCountedGarbageCollected<MediaSource>);
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(MediaSource);
 public:
     static const AtomicString& openKeyword();