Re-enable solid background color optimization for composited layers.

Source/core/platform/graphics/GraphicsLayer.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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
@@ skipping 208 matching lines @@
     // These methods handle both transitions and keyframe animations.
     bool addAnimation(PassOwnPtr<blink::WebAnimation>);
     void pauseAnimation(int animationId, double /*timeOffset*/);
     void removeAnimation(int animationId);
 
     // Layer contents
     void setContentsToImage(Image*);
     void setContentsToNinePatch(Image*, const IntRect& aperture);
     bool shouldDirectlyCompositeImage(Image*) const { return true; }
     // Pass an invalid color to remove the contents layer.
-    void setContentsToSolidColor(const Color&) { }
+    void setContentsToSolidColor(const Color&);
     void setContentsToPlatformLayer(blink::WebLayer* layer) { setContentsTo(layer); }
     bool hasContentsLayer() const { return m_contentsLayer; }
 
     // Callback from the underlying graphics system to draw layer contents.
     void paintGraphicsLayerContents(GraphicsContext&, const IntRect& clip);
     // Callback from the underlying graphics system when the layer has been displayed
     void layerDidDisplay(blink::WebLayer*) { }
 
     // For hosting this GraphicsLayer in a native layer hierarchy.
     blink::WebLayer* platformLayer() const;
@@ skipping 22 matching lines @@
     // Return a string with a human readable form of the layer tree, If debug is true
     // pointers for the layers and timing data will be included in the returned string.
     String layerTreeAsText(LayerTreeFlags = LayerTreeNormal) const;
 
     // Return an estimate of the backing store memory cost (in bytes). May be incorrect for tiled layers.
     double backingStoreMemoryEstimate() const;
 
     void resetTrackedRepaints();
     void addRepaintRect(const FloatRect&);
 
-    static bool supportsBackgroundColorContent()
-    {
-        return false;
-    }
-
     void addLinkHighlight(LinkHighlightClient*);
     void removeLinkHighlight(LinkHighlightClient*);
     // Exposed for tests
     unsigned numLinkHighlights() { return m_linkHighlights.size(); }
     LinkHighlightClient* linkHighlight(int i) { return m_linkHighlights[i]; }
 
     void setScrollableArea(ScrollableArea*, bool isMainFrame);
     ScrollableArea* scrollableArea() const { return m_scrollableArea; }
 
     blink::WebContentLayer* contentLayer() const { return m_layer.get(); }
@@ skipping 90 matching lines @@
     GraphicsLayer* m_replicatedLayer; // For a replica layer, a reference to the original layer.
     FloatPoint m_replicatedLayerPosition; // For a replica layer, the position of the replica.
 
     IntRect m_contentsRect;
 
     int m_paintCount;
 
     OwnPtr<blink::WebContentLayer> m_layer;
     OwnPtr<blink::WebImageLayer> m_imageLayer;
     OwnPtr<blink::WebNinePatchLayer> m_ninePatchLayer;
+    Color m_contentsSolidColor;
+    OwnPtr<blink::WebSolidColorLayer> m_solidColorLayer;
     blink::WebLayer* m_contentsLayer;
     // We don't have ownership of m_contentsLayer, but we do want to know if a given layer is the
     // same as our current layer in setContentsTo(). Since m_contentsLayer may be deleted at this point,
     // we stash an ID away when we know m_contentsLayer is alive and use that for comparisons from that point
     // on.
     int m_contentsLayerId;
 
     Vector<LinkHighlightClient*> m_linkHighlights;
 
     OwnPtr<OpaqueRectTrackingContentLayerDelegate> m_opaqueRectTrackingContentLayerDelegate;
 
     ScrollableArea* m_scrollableArea;
     blink::WebCompositingReasons m_compositingReasons;
 };
 
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showGraphicsLayerTree(const WebCore::GraphicsLayer* layer);
 #endif
 
 #endif // GraphicsLayer_h