Drop background color optimization for composited layers

Source/core/rendering/compositing/CompositedLayerMapping.h

Index: Source/core/rendering/compositing/CompositedLayerMapping.h
diff --git a/Source/core/rendering/compositing/CompositedLayerMapping.h b/Source/core/rendering/compositing/CompositedLayerMapping.h
index c0d9a2a8e9f667b3e6d34559710514a810863775..9e29760cf09ff10af70383b110bd02e2849be7db 100644
--- a/Source/core/rendering/compositing/CompositedLayerMapping.h
+++ b/Source/core/rendering/compositing/CompositedLayerMapping.h
@@ -191,7 +191,6 @@ public:
 #endif
 
     LayoutRect contentsBox() const;
-    IntRect backgroundBox() const;
 
     // For informative purposes only.
     CompositingLayerType compositingLayerType() const;
@@ -233,7 +232,7 @@ private:
     void updateScrollParent(RenderLayer*);
     void updateClipParent(RenderLayer*);
     bool updateSquashingLayers(bool needsSquashingLayers);
-    void updateDrawsContent(bool isSimpleContainer);
+    void updateDrawsContent();
     void updateChildrenTransform();
     void registerScrollingLayers();
 
@@ -260,20 +259,19 @@ private:
 
     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(bool isSimpleContainer) const;
+    bool containsPaintedContent() const;
+    // Returns true if this layer has content that needs to be rendered by its own reasons such as box decoration, non-composited visible children, and etc..

[alokp, 2014/02/27 19:22:27]

The comment is still not clear to me. How is it different from
containsPaintedContent? Does this take subtree into account while
containsPaintedContent does not?

The function name sounds like !(paintsIntoCompositedAncestor).

[dshwang, 2014/02/27 19:50:53]

How about hasVisibleContentOrNonCompositingDescendantLayers()?

Actually, paintsIntoOwningLayer() is a subset of containsPaintedContent().

+    bool paintsIntoOwningLayer() 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(bool isSimpleContainer);
-    void updateContentsRect(bool isSimpleContainer);
+    void updateBackgroundColor();
+    void updateContentsRect();
 
     void updateCompositingReasons();