Add support for accelerated fixed root background

Source/core/rendering/RenderLayerBacking.h

 /*
  * Copyright (C) 2009, 2010, 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 67 matching lines @@
     GraphicsLayer* graphicsLayer() const { return m_graphicsLayer.get(); }
 
     // Layer to clip children
     bool hasClippingLayer() const { return m_childContainmentLayer; }
     GraphicsLayer* clippingLayer() const { return m_childContainmentLayer.get(); }
 
     // Layer to get clipped by ancestor
     bool hasAncestorClippingLayer() const { return m_ancestorClippingLayer != 0; }
     GraphicsLayer* ancestorClippingLayer() const { return m_ancestorClippingLayer.get(); }
 
-    GraphicsLayer* contentsContainmentLayer() const { return m_contentsContainmentLayer.get(); }
-
     bool hasContentsLayer() const { return m_foregroundLayer != 0; }
     GraphicsLayer* foregroundLayer() const { return m_foregroundLayer.get(); }
 
     GraphicsLayer* backgroundLayer() const { return m_backgroundLayer.get(); }
     bool backgroundLayerPaintsFixedRootBackground() const { return m_backgroundLayerPaintsFixedRootBackground; }
     
     bool hasScrollingLayer() const { return m_scrollingLayer; }
     GraphicsLayer* scrollingLayer() const { return m_scrollingLayer.get(); }
     GraphicsLayer* scrollingContentsLayer() const { return m_scrollingContentsLayer.get(); }
 
@@ skipping 134 matching lines @@
     bool shouldClipCompositedBounds() const;
 
     void paintIntoLayer(const GraphicsLayer*, GraphicsContext*, const IntRect& paintDirtyRect, PaintBehavior, GraphicsLayerPaintingPhase);
 
     static CSSPropertyID graphicsLayerToCSSProperty(AnimatedPropertyID);
     static AnimatedPropertyID cssToGraphicsLayerProperty(CSSPropertyID);
 
     RenderLayer* m_owningLayer;
 
     OwnPtr<GraphicsLayer> m_ancestorClippingLayer; // Only used if we are clipped by an ancestor which is not a stacking context.
-    OwnPtr<GraphicsLayer> m_contentsContainmentLayer; // Only used if we have a background layer; takes the transform.
     OwnPtr<GraphicsLayer> m_graphicsLayer;
     OwnPtr<GraphicsLayer> m_foregroundLayer; // Only used in cases where we need to draw the foreground separately.
     OwnPtr<GraphicsLayer> m_backgroundLayer; // Only used in cases where we need to draw the background separately.
     OwnPtr<GraphicsLayer> m_childContainmentLayer; // Only used if we have clipping on a stacking context with compositing children, or if the layer has a tile cache.
     OwnPtr<GraphicsLayer> m_maskLayer; // Only used if we have a mask.
 
     OwnPtr<GraphicsLayer> m_layerForHorizontalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForVerticalScrollbar;
     OwnPtr<GraphicsLayer> m_layerForScrollCorner;
 
     OwnPtr<GraphicsLayer> m_scrollingLayer; // Only used if the layer is using composited scrolling.
     OwnPtr<GraphicsLayer> m_scrollingContentsLayer; // Only used if the layer is using composited scrolling.
 
     uint64_t m_scrollLayerID;
 
     IntRect m_compositedBounds;
 
     bool m_artificiallyInflatedBounds; // bounds had to be made non-zero to make transform-origin work
     bool m_boundsConstrainedByClipping;
     bool m_isMainFrameRenderViewLayer;
     bool m_requiresOwnBackingStore;
     bool m_canCompositeFilters;
     bool m_backgroundLayerPaintsFixedRootBackground;
 };
 
 } // namespace WebCore
 
 #endif // RenderLayerBacking_h