Move the Widget hierarchy to the Oilpan heap.

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 2011 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 223 matching lines @@
     if (OwnPtr<WebScrollbarLayer> scrollbarLayer = scrollbars.take(scrollableArea))
         GraphicsLayer::unregisterContentsLayer(scrollbarLayer->layer());
 }
 
 static PassOwnPtr<WebScrollbarLayer> createScrollbarLayer(Scrollbar* scrollbar)
 {
     ScrollbarTheme* theme = scrollbar->theme();
     blink::WebScrollbarThemePainter painter(theme, scrollbar);
     OwnPtr<blink::WebScrollbarThemeGeometry> geometry(blink::WebScrollbarThemeGeometryNative::create(theme));
 
-    OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createScrollbarLayer(new blink::WebScrollbarImpl(scrollbar), painter, geometry.leakPtr()));
+    OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createScrollbarLayer(WebScrollbarImpl::create(scrollbar), painter, geometry.leakPtr()));
     GraphicsLayer::registerContentsLayer(scrollbarLayer->layer());
     return scrollbarLayer.release();
 }
 
 PassOwnPtr<WebScrollbarLayer> ScrollingCoordinator::createSolidColorScrollbarLayer(ScrollbarOrientation orientation, int thumbThickness, int trackStart, bool isLeftSideVerticalScrollbar)
 {
     blink::WebScrollbar::Orientation webOrientation = (orientation == HorizontalScrollbar) ? blink::WebScrollbar::Horizontal : blink::WebScrollbar::Vertical;
     OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createSolidColorScrollbarLayer(webOrientation, thumbThickness, trackStart, isLeftSideVerticalScrollbar));
     GraphicsLayer::registerContentsLayer(scrollbarLayer->layer());
     return scrollbarLayer.release();
@@ skipping 462 matching lines @@
     if (const FrameView::ResizerAreaSet* resizerAreas = frameView->resizerAreas()) {
         for (FrameView::ResizerAreaSet::const_iterator it = resizerAreas->begin(), end = resizerAreas->end(); it != end; ++it) {
             RenderBox* box = *it;
             IntRect bounds = box->absoluteBoundingBoxRect();
             IntRect corner = box->layer()->scrollableArea()->touchResizerCornerRect(bounds);
             corner.moveBy(offset);
             shouldHandleScrollGestureOnMainThreadRegion.unite(corner);
         }
     }
 
-    if (const HashSet<RefPtr<Widget> >* children = frameView->children()) {
-        for (HashSet<RefPtr<Widget> >::const_iterator it = children->begin(), end = children->end(); it != end; ++it) {
+    if (const WillBeHeapHashSet<RefPtrWillBeMember<Widget> >* children = frameView->children()) {
+        for (WillBeHeapHashSet<RefPtrWillBeMember<Widget> >::const_iterator it = children->begin(), end = children->end(); it != end; ++it) {
             if (!(*it)->isPluginView())
                 continue;
 
             PluginView* pluginView = toPluginView(it->get());
             if (pluginView->wantsWheelEvents())
                 shouldHandleScrollGestureOnMainThreadRegion.unite(pluginView->frameRect());
         }
     }
 
     const FrameTree& tree = frame->tree();
@@ skipping 230 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : 0)
         return blink::WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace blink