Prioritize tiles near the viewport in out-of-viewport layers

cc/resources/picture_layer_tiling.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_RESOURCES_PICTURE_LAYER_TILING_H_
 #define CC_RESOURCES_PICTURE_LAYER_TILING_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 58 matching lines @@
          it != tiles_.end(); ++it)
       all_tiles.push_back(it->second);
     return all_tiles;
   }
 
   static gfx::Rect ExpandRectEquallyToAreaBoundedBy(
       gfx::Rect starting_rect,
       int64 target_area,
       gfx::Rect bounding_rect);
 
+  static gfx::Rect ExpandRectBySizeBoundedBy(
+      gfx::Rect starting_rect,
+      int horizontal_expansion,
+      int vertical_expansion,
+      gfx::Rect bounding_rect);
+
   // Iterate over all tiles to fill content_rect.  Even if tiles are invalid
   // (i.e. no valid resource) this tiling should still iterate over them.
   // The union of all geometry_rect calls for each element iterated over should
   // exactly equal content_rect and no two geometry_rects should intersect.
   class CC_EXPORT CoverageIterator {
    public:
     CoverageIterator();
     CoverageIterator(const PictureLayerTiling* tiling,
         float dest_scale,
         gfx::Rect rect);
@@ skipping 81 matching lines @@
 
   friend class CoverageIterator;
 
  private:
   DISALLOW_ASSIGN(PictureLayerTiling);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_LAYER_TILING_H_