Oilpan: Replace most of RefPtrs for Event objects with oilpan's transition types

Source/modules/mediasource/MediaSourceBase.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 328 matching lines @@
     }
 
     ASSERT_NOT_REACHED();
     return nullptr;
 }
 
 void MediaSourceBase::scheduleEvent(const AtomicString& eventName)
 {
     ASSERT(m_asyncEventQueue);
 
-    RefPtr<Event> event = Event::create(eventName);
+    RefPtrWillBeRawPtr<Event> event = Event::create(eventName);
     event->setTarget(this);
 
     m_asyncEventQueue->enqueueEvent(event.release());
 }
 
 ExecutionContext* MediaSourceBase::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
 URLRegistry& MediaSourceBase::registry() const
 {
     return MediaSourceRegistry::registry();
 }
 
 }