Keeping track of descendants that draw content instead of recalcualting

cc/layers/picture_image_layer.h

Index: cc/layers/picture_image_layer.h
diff --git a/cc/layers/picture_image_layer.h b/cc/layers/picture_image_layer.h
index 69b89d1b68ac34c2a644461ba643fcc3f89b8782..0b3e32c404ff8f41e020de722dc527d0fd38c587 100644
--- a/cc/layers/picture_image_layer.h
+++ b/cc/layers/picture_image_layer.h
@@ -22,7 +22,6 @@ class CC_EXPORT PictureImageLayer : public PictureLayer, ContentLayerClient {
   // Layer implementation.
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(
       LayerTreeImpl* tree_impl) OVERRIDE;
-  virtual bool DrawsContent() const OVERRIDE;
 
   // ContentLayerClient implementation.
   virtual void PaintContents(
@@ -33,6 +32,9 @@ class CC_EXPORT PictureImageLayer : public PictureLayer, ContentLayerClient {
   virtual void DidChangeLayerCanUseLCDText() OVERRIDE {}
   virtual bool FillsBoundsCompletely() const OVERRIDE;
 
+ protected:
+  virtual bool HasDrawableContent() const OVERRIDE;
+
  private:
   PictureImageLayer();
   virtual ~PictureImageLayer();