cc: Fix comment about update rect. This rect is in layer space.

cc/layers/layer_impl.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_LAYER_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <set>
 #include <string>
 
@@ skipping 607 matching lines @@
 
   FilterOperations filters_;
   FilterOperations background_filters_;
 
  protected:
   DrawMode current_draw_mode_;
 
  private:
   // Rect indicating what was repainted/updated during update.
   // Note that plugin layers bypass this and leave it empty.
-  // Uses layer's content space.
+  // Uses layer (not content) space.
   gfx::RectF update_rect_;
 
   // Manages animations for this layer.
   scoped_refptr<LayerAnimationController> layer_animation_controller_;
 
   // Manages scrollbars for this layer
   scoped_ptr<ScrollbarAnimationController> scrollbar_animation_controller_;
 
   // Weak pointers to this layer's scrollbars, if it has them. Updated during
   // tree synchronization.
   ScrollbarLayerImplBase* horizontal_scrollbar_layer_;
   ScrollbarLayerImplBase* vertical_scrollbar_layer_;
 
   ScopedPtrVector<CopyOutputRequest> copy_requests_;
 
   // Group of properties that need to be computed based on the layer tree
   // hierarchy before layers can be drawn.
   DrawProperties<LayerImpl> draw_properties_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_