cc: Fix layer raster tile iterator not to skip a tile erroneously.

cc/layers/picture_layer_impl.h

 // Copyright 2012 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_PICTURE_LAYER_IMPL_H_
 #define CC_LAYERS_PICTURE_LAYER_IMPL_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 33 matching lines @@
     ~LayerRasterTileIterator();
 
     Tile* operator*();
     const Tile* operator*() const;
     LayerRasterTileIterator& operator++();
     operator bool() const;
 
    private:
     enum IteratorType { LOW_RES, HIGH_RES, NUM_ITERATORS };
 
+    void AdvanceToNextStage();
+
     PictureLayerImpl* layer_;
 
     struct IterationStage {
       IteratorType iterator_type;
       TilePriority::PriorityBin tile_type;
     };
 
     size_t current_stage_;
 
     // One low res stage, and three high res stages.
@@ skipping 164 matching lines @@
   gfx::Rect viewport_rect_for_tile_priority_;
   gfx::Transform screen_space_transform_for_tile_priority_;
 
   friend class PictureLayer;
   DISALLOW_COPY_AND_ASSIGN(PictureLayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_PICTURE_LAYER_IMPL_H_