Remove more oilpan.

sky/engine/core/dom/custom/CustomElementMicrotaskDispatcher.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CustomElementMicrotaskDispatcher_h
 #define CustomElementMicrotaskDispatcher_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class CustomElementCallbackQueue;
 class CustomElementMicrotaskImportStep;
 class CustomElementMicrotaskStep;
 class Document;
 class HTMLImportLoader;
 
-class CustomElementMicrotaskDispatcher final : public DummyBase<CustomElementMicrotaskDispatcher> {
+class CustomElementMicrotaskDispatcher final {
     WTF_MAKE_NONCOPYABLE(CustomElementMicrotaskDispatcher);
     DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(CustomElementMicrotaskDispatcher);
 public:
     static CustomElementMicrotaskDispatcher& instance();
 
     void enqueue(CustomElementCallbackQueue*);
 
     bool elementQueueIsEmpty() { return m_elements.isEmpty(); }
 
     void trace(Visitor*);
@@ skipping 13 matching lines @@
         Resolving,
         DispatchingCallbacks
     } m_phase;
 
     Vector<RawPtr<CustomElementCallbackQueue> > m_elements;
 };
 
 }
 
 #endif // CustomElementMicrotaskDispatcher_h