Re-land: cc: Examine layers to determine if we're ready to activate.

cc/layers/picture_layer_impl.h

Index: cc/layers/picture_layer_impl.h
diff --git a/cc/layers/picture_layer_impl.h b/cc/layers/picture_layer_impl.h
index 80d09dde721ad2e533c11d819f4241e986c6327c..8a5c54be03d0cd69a8e7f6a60a6678c699e57d19 100644
--- a/cc/layers/picture_layer_impl.h
+++ b/cc/layers/picture_layer_impl.h
@@ -93,7 +93,7 @@ class CC_EXPORT PictureLayerImpl
   virtual void AppendQuads(QuadSink* quad_sink,
                            AppendQuadsData* append_quads_data) OVERRIDE;
   virtual void UpdateTilePriorities() OVERRIDE;
-  virtual void NotifyTileInitialized(const Tile* tile) OVERRIDE;
+  virtual void NotifyTileStateChanged(const Tile* tile) OVERRIDE;
   virtual void DidBecomeActive() OVERRIDE;
   virtual void DidBeginTracing() OVERRIDE;
   virtual void ReleaseResources() OVERRIDE;
@@ -141,6 +141,7 @@ class CC_EXPORT PictureLayerImpl
   PictureLayerImpl* GetTwinLayer() { return twin_layer_; }
   WhichTree GetTree() const;
   bool IsOnActiveOrPendingTree() const;
+  bool AllTilesRequiredForActivationAreReadyToDraw() const;
 
  protected:
   friend class LayerRasterTileIterator;