Oilpan: move RenderObjects off heap.

Source/core/rendering/RenderScrollbar.cpp

 /*
  * 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 46 matching lines @@
         part->layout();
         rect.setSize(flooredIntSize(part->size()));
     } else if (this->orientation() == HorizontalScrollbar) {
         rect.setWidth(this->width());
     } else {
         rect.setHeight(this->height());
     }
 
     setFrameRect(rect);
 
-#if ENABLE(OILPAN)
-    ThreadState::current()->registerPreFinalizer(*this);
-#endif
 }
 
 RenderScrollbar::~RenderScrollbar()
 {
-    // Oilpan: to be able to access the hash map that's
-    // also on the heap, a pre-destruction finalizer is used.
-#if !ENABLE(OILPAN)
-    destroyParts();
-#endif
-}
-
-void RenderScrollbar::destroyParts()
-{
     if (m_parts.isEmpty())
         return;
 
     // When a scrollbar is detached from its parent (causing all parts removal) and
     // ready to be destroyed, its destruction can be delayed because of RefPtr
     // maintained in other classes such as EventHandler (m_lastScrollbarUnderMouse).
     // Meanwhile, we can have a call to updateScrollbarPart which recreates the
     // scrollbar part. So, we need to destroy these parts since we don't want them
     // to call on a destroyed scrollbar. See webkit bug 68009.
     updateScrollbarParts(true);
 }
 
 void RenderScrollbar::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_owner);
     visitor->trace(m_owningFrame);
-    visitor->trace(m_parts);
 #endif
     Scrollbar::trace(visitor);
 }
 
 RenderBox* RenderScrollbar::owningRenderer() const
 {
     if (m_owningFrame) {
         RenderBox* currentRenderer = m_owningFrame->ownerRenderer();
         return currentRenderer;
     }
@@ skipping 249 matching lines @@
 int RenderScrollbar::minimumThumbLength()
 {
     RenderScrollbarPart* partRenderer = m_parts.get(ThumbPart);
     if (!partRenderer)
         return 0;
     partRenderer->layout();
     return orientation() == HorizontalScrollbar ? partRenderer->size().width() : partRenderer->size().height();
 }
 
 }