cc: Add support for partial swaps when using impl-side painting.

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 64be55ceae4fa38ee853913895e39122acb7bd9f..7c53eb7ee2e8660cbe596eef0853b3c667cf909e 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -453,6 +453,12 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
 
   const gfx::RectF& update_rect() const { return update_rect_; }
 
+  void SetInitializedTileRect(gfx::Rect initialized_tile_rect);

[reveman, 2014/04/11 18:11:34]

I'm not a fan of "InitializedTile" name. This is the general layer class. The
usage of tiles is picturelayer specific implementation detail. How about simply
"SetDamageRect"?

[sohanjg, 2014/04/14 10:16:11]

Done.

+
+  const gfx::Rect& initialized_tile_rect() const {
+    return initialized_tile_rect_;
+  }
+
   virtual base::DictionaryValue* LayerTreeAsJson() const;
 
   void SetStackingOrderChanged(bool stacking_order_changed);
@@ -651,6 +657,8 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
   // Uses layer (not content) space.
   gfx::RectF update_rect_;
 
+  gfx::Rect initialized_tile_rect_;
+
   // Manages animations for this layer.
   scoped_refptr<LayerAnimationController> layer_animation_controller_;