Revert of cc: Remove WorkerPool class and instead use TaskGraphRunner directly.

cc/resources/tile_manager.cc

 // 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.
 
 #include "cc/resources/tile_manager.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
@@ skipping 154 matching lines @@
 
 // static
 scoped_ptr<TileManager> TileManager::Create(
     TileManagerClient* client,
     ResourceProvider* resource_provider,
     ContextProvider* context_provider,
     RenderingStatsInstrumentation* rendering_stats_instrumentation,
     bool use_map_image,
     size_t max_transfer_buffer_usage_bytes,
     size_t max_raster_usage_bytes,
-    unsigned map_image_texture_target) {
+    GLenum map_image_texture_target) {
   return make_scoped_ptr(
       new TileManager(client,
                       resource_provider,
                       use_map_image ?
                       ImageRasterWorkerPool::Create(
                           resource_provider,
                           context_provider,
                           map_image_texture_target) :
                       PixelBufferRasterWorkerPool::Create(
                           resource_provider,
@@ skipping 795 matching lines @@
                                                          flags));
   DCHECK(tiles_.find(tile->id()) == tiles_.end());
 
   tiles_[tile->id()] = tile;
   used_layer_counts_[tile->layer_id()]++;
   prioritized_tiles_dirty_ = true;
   return tile;
 }
 
 }  // namespace cc