cc: Low quality support for low res tiles

cc/resources/tile.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_TILE_H_
 #define CC_RESOURCES_TILE_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 17 matching lines @@
        gfx::Rect content_rect,
        gfx::Rect opaque_rect,
        float contents_scale,
        int layer_id,
        int source_frame_number);
 
   PicturePileImpl* picture_pile() {
     return picture_pile_.get();
   }
 
+  const PicturePileImpl* picture_pile() const {
+    return picture_pile_.get();
+  }
+
   const TilePriority& priority(WhichTree tree) const {
     return priority_[tree];
   }
 
   TilePriority combined_priority() const {
     return TilePriority(priority_[ACTIVE_TREE],
                         priority_[PENDING_TREE]);
   }
 
   void SetPriority(WhichTree tree, const TilePriority& priority) {
@@ skipping 69 matching lines @@
   ManagedTileState managed_state_;
   int layer_id_;
   int source_frame_number_;
 
   DISALLOW_COPY_AND_ASSIGN(Tile);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_H_