Oilpan: make DOMWindowProperty a GC mixin.

Source/core/frame/BarProp.h

 /*
  * Copyright (C) 2007 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
@@ skipping 21 matching lines @@
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/frame/DOMWindowProperty.h"
 #include "platform/heap/Handle.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace blink {
 
 class LocalFrame;
 
-class BarProp FINAL : public RefCountedWillBeGarbageCollectedFinalized<BarProp>, public ScriptWrappable, public DOMWindowProperty {
+class BarProp FINAL : public RefCountedWillBeGarbageCollected<BarProp>, public ScriptWrappable, public DOMWindowProperty {
     DEFINE_WRAPPERTYPEINFO();
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(BarProp);
 public:
     enum Type { Locationbar, Menubar, Personalbar, Scrollbars, Statusbar, Toolbar };
 
     static PassRefPtrWillBeRawPtr<BarProp> create(LocalFrame* frame, Type type)
     {
         return adoptRefWillBeNoop(new BarProp(frame, type));
     }
 
     bool visible() const;
 
-    void trace(Visitor*) { }
+    virtual void trace(Visitor*) OVERRIDE;
 
 private:
     BarProp(LocalFrame*, Type);
     Type m_type;
 };
 
 } // namespace blink
 
 #endif // BarProp_h