cc: Speed up CleanUpImageDecodeTasks a bit.

cc/resources/tile_manager.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_MANAGER_H_
 #define CC_RESOURCES_TILE_MANAGER_H_
 
 #include <queue>
 #include <set>
 #include <vector>
@@ skipping 75 matching lines @@
 
       tile_version.resource_ = make_scoped_ptr(
           new ResourcePool::Resource(resource_provider,
                                      gfx::Size(1, 1),
                                      resource_provider->best_texture_format()));
 
       bytes_releasable_ += tiles[i]->bytes_consumed_if_allocated();
       ++resources_releasable_;
     }
   }
+  RasterWorkerPool* RasterWorkerPoolForTesting() {
+    return raster_worker_pool_.get();
+  }
 
  protected:
   TileManager(TileManagerClient* client,
               ResourceProvider* resource_provider,
               scoped_ptr<RasterWorkerPool> raster_worker_pool,
               size_t num_raster_threads,
               RenderingStatsInstrumentation* rendering_stats_instrumentation);
 
   // Methods called by Tile
   friend class Tile;
@@ skipping 63 matching lines @@
   MemoryHistory::Entry memory_stats_from_last_assign_;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation_;
 
   bool did_initialize_visible_tile_;
 
   typedef base::hash_map<uint32_t, RasterWorkerPool::Task> PixelRefTaskMap;
   typedef base::hash_map<int, PixelRefTaskMap> LayerPixelRefTaskMap;
   LayerPixelRefTaskMap image_decode_tasks_;
 
+  typedef base::hash_map<int, int> LayerCountMap;
+  LayerCountMap used_layer_counts_;
+
   RasterTaskCompletionStats update_visible_tiles_stats_;
 
   DISALLOW_COPY_AND_ASSIGN(TileManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TILE_MANAGER_H_