Revert 168245 "Drop background color optimization for composited..."

trunk/Source/core/rendering/compositing/CompositedLayerMapping.h

Index: trunk/Source/core/rendering/compositing/CompositedLayerMapping.h
===================================================================
--- trunk/Source/core/rendering/compositing/CompositedLayerMapping.h	(revision 168316)
+++ trunk/Source/core/rendering/compositing/CompositedLayerMapping.h	(working copy)
@@ -184,6 +184,7 @@
 #endif
 
     LayoutRect contentsBox() const;
+    IntRect backgroundBox() const;
 
     GraphicsLayer* layerForHorizontalScrollbar() const { return m_layerForHorizontalScrollbar.get(); }
     GraphicsLayer* layerForVerticalScrollbar() const { return m_layerForVerticalScrollbar.get(); }
@@ -222,7 +223,7 @@
     void updateScrollParent(RenderLayer*);
     void updateClipParent(RenderLayer*);
     bool updateSquashingLayers(bool needsSquashingLayers);
-    void updateDrawsContent();
+    void updateDrawsContent(bool isSimpleContainer);
     void updateChildrenTransform();
     void registerScrollingLayers();
 
@@ -249,17 +250,20 @@
 
     bool isMainFrameRenderViewLayer() const;
 
+    bool paintsBoxDecorations() const;
     bool paintsChildren() const;
 
+    // Returns true if this compositing layer has no visible content.
+    bool isSimpleContainerCompositingLayer() const;
     // Returns true if this layer has content that needs to be rendered by painting into the backing store.
-    bool containsPaintedContent() const;
+    bool containsPaintedContent(bool isSimpleContainer) const;
     // Returns true if the RenderLayer just contains an image that we can composite directly.
     bool isDirectlyCompositedImage() const;
     void updateImageContents();
 
     Color rendererBackgroundColor() const;
-    void updateBackgroundColor();
-    void updateContentsRect();
+    void updateBackgroundColor(bool isSimpleContainer);
+    void updateContentsRect(bool isSimpleContainer);
 
     void updateCompositingReasons();