Oilpan: tidy up prefinalizer declarations and a registration.

Source/core/rendering/RenderScrollbar.h

 /*
  * Copyright (C) 2008, 2009 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 22 matching lines @@
 
 namespace blink {
 
 class LocalFrame;
 class Node;
 class RenderBox;
 class RenderScrollbarPart;
 class RenderStyle;
 
 class RenderScrollbar final : public Scrollbar {
-#if ENABLE(OILPAN)
-    USING_PRE_FINALIZER(RenderScrollbar, destroyParts);
-#endif
+    WILL_BE_USING_PRE_FINALIZER(RenderScrollbar, destroyParts);
 public:
     static PassRefPtrWillBeRawPtr<Scrollbar> createCustomScrollbar(ScrollableArea*, ScrollbarOrientation, Node*, LocalFrame* owningFrame = 0);
     virtual ~RenderScrollbar();
 
     RenderBox* owningRenderer() const;
 
     IntRect buttonRect(ScrollbarPart);
     IntRect trackRect(int startLength, int endLength);
     IntRect trackPieceRectWithMargins(ScrollbarPart, const IntRect&);
 
@@ skipping 37 matching lines @@
     RawPtrWillBeMember<LocalFrame> m_owningFrame;
 
     WillBeHeapHashMap<unsigned, RawPtrWillBeMember<RenderScrollbarPart> > m_parts;
 };
 
 DEFINE_TYPE_CASTS(RenderScrollbar, ScrollbarThemeClient, scrollbar, scrollbar->isCustomScrollbar(), scrollbar.isCustomScrollbar());
 
 } // namespace blink
 
 #endif // RenderScrollbar_h