Keeping track of descendants that draw content instead of recalcualting

cc/layers/tiled_layer.h

Index: cc/layers/tiled_layer.h
diff --git a/cc/layers/tiled_layer.h b/cc/layers/tiled_layer.h
index e272497e7ef4602dde756d6843fb2634bc5d11e7..4a83e457e0f1c760c6914f1250670db41e6b342a 100644
--- a/cc/layers/tiled_layer.h
+++ b/cc/layers/tiled_layer.h
@@ -27,7 +27,6 @@ class CC_EXPORT TiledLayer : public ContentsScalingLayer {
   // Layer implementation.
   virtual void SetIsMask(bool is_mask) OVERRIDE;
   virtual void PushPropertiesTo(LayerImpl* layer) OVERRIDE;
-  virtual bool DrawsContent() const OVERRIDE;
   virtual void ReduceMemoryUsage() OVERRIDE;
   virtual void SetNeedsDisplayRect(const gfx::RectF& dirty_rect) OVERRIDE;
   virtual void SetLayerTreeHost(LayerTreeHost* layer_tree_host) OVERRIDE;
@@ -68,6 +67,8 @@ class CC_EXPORT TiledLayer : public ContentsScalingLayer {
 
   bool SkipsDraw() const { return skips_draw_; }
 
+  virtual bool HasDrawableContent() const OVERRIDE;
+
   // Virtual for testing
   virtual PrioritizedResourceManager* ResourceManager();
   const LayerTilingData* TilerForTesting() const { return tiler_.get(); }