Remove more oilpan.

sky/engine/core/dom/MutationObserverRegistration.h

 /*
  * Copyright (C) 2011 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 23 matching lines @@
 #include "core/dom/MutationObserver.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace blink {
 
 class QualifiedName;
 
-class MutationObserverRegistration final : public DummyBase<MutationObserverRegistration> {
+class MutationObserverRegistration final {
 public:
     static PassOwnPtr<MutationObserverRegistration> create(MutationObserver&, Node*, MutationObserverOptions, const HashSet<AtomicString>& attributeFilter);
     ~MutationObserverRegistration();
 
     void resetObservation(MutationObserverOptions, const HashSet<AtomicString>& attributeFilter);
     void observedSubtreeNodeWillDetach(Node&);
     void clearTransientRegistrations();
     bool hasTransientRegistrations() const { return m_transientRegistrationNodes && !m_transientRegistrationNodes->isEmpty(); }
     void unregister();
 
@@ skipping 17 matching lines @@
     typedef HashSet<RefPtr<Node> > NodeHashSet;
     OwnPtr<NodeHashSet> m_transientRegistrationNodes;
 
     MutationObserverOptions m_options;
     HashSet<AtomicString> m_attributeFilter;
 };
 
 } // namespace blink
 
 #endif // MutationObserverRegistration_h