Oilpan: have DOMException be on the heap by default.

Source/modules/encryptedmedia/MediaKeySession.h

 /*
  * Copyright (C) 2013 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 11 matching lines @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef MediaKeySession_h
 #define MediaKeySession_h
 
 #include "bindings/core/v8/ScriptPromiseProperty.h"
 #include "core/dom/ActiveDOMObject.h"
 #include "core/dom/DOMArrayPiece.h"
-#include "core/dom/DOMException.h"
 #include "modules/EventTargetModules.h"
 #include "modules/encryptedmedia/MediaKeyStatusMap.h"
 #include "platform/Timer.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/WebContentDecryptionModuleSession.h"
 #include "public/platform/WebEncryptedMediaTypes.h"
 
 namespace blink {
 
+class DOMException;
 class GenericEventQueue;
 class MediaKeys;
 
 // References are held by JS only. However, even if all JS references are
 // dropped, it won't be garbage collected until close event received or
 // MediaKeys goes away (as determined by a WeakMember reference). This allows
 // the CDM to continue to fire events for this session, as long as the session
 // is open.
 //
 // WeakMember<MediaKeys> is used instead of having MediaKeys and MediaKeySession
@@ skipping 71 matching lines @@
     WebEncryptedMediaSessionType m_sessionType;
     double m_expiration;
     Member<MediaKeyStatusMap> m_keyStatusesMap;
 
     // Session states.
     bool m_isUninitialized;
     bool m_isCallable;
     bool m_isClosed; // Is the CDM finished with this session?
 
     // Keep track of the closed promise.
-    typedef ScriptPromiseProperty<Member<MediaKeySession>, ToV8UndefinedGenerator, RefPtrWillBeMember<DOMException>> ClosedPromise;
+    typedef ScriptPromiseProperty<Member<MediaKeySession>, ToV8UndefinedGenerator, Member<DOMException>> ClosedPromise;
     Member<ClosedPromise> m_closedPromise;
 
     HeapDeque<Member<PendingAction>> m_pendingActions;
     Timer<MediaKeySession> m_actionTimer;
 };
 
 } // namespace blink
 
 #endif // MediaKeySession_h