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

cc/resources/pixel_buffer_raster_worker_pool.h

 // Copyright 2013 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_PIXEL_BUFFER_RASTER_WORKER_POOL_H_
 #define CC_RESOURCES_PIXEL_BUFFER_RASTER_WORKER_POOL_H_
 
 #include <deque>
 #include <set>
 #include <vector>
 
-#include "base/cancelable_callback.h"
 #include "base/containers/hash_tables.h"
 #include "cc/resources/raster_worker_pool.h"
 
 namespace cc {
 
 class CC_EXPORT PixelBufferRasterWorkerPool : public RasterWorkerPool {
  public:
   virtual ~PixelBufferRasterWorkerPool();
 
   static scoped_ptr<RasterWorkerPool> Create(
       ResourceProvider* resource_provider,
       ContextProvider* context_provider,
       size_t max_transfer_buffer_usage_bytes) {
     return make_scoped_ptr<RasterWorkerPool>(
         new PixelBufferRasterWorkerPool(resource_provider,
                                         context_provider,
                                         max_transfer_buffer_usage_bytes));
   }
 
   // Overridden from WorkerPool:
   virtual void Shutdown() OVERRIDE;
 
   // Overridden from RasterWorkerPool:
   virtual void ScheduleTasks(RasterTask::Queue* queue) OVERRIDE;
-  virtual unsigned GetResourceTarget() const OVERRIDE;
+  virtual GLenum GetResourceTarget() const OVERRIDE;
   virtual ResourceFormat GetResourceFormat() const OVERRIDE;
   virtual void CheckForCompletedTasks() OVERRIDE;
   virtual void OnRasterTasksFinished() OVERRIDE;
   virtual void OnRasterTasksRequiredForActivationFinished() OVERRIDE;
 
  private:
   PixelBufferRasterWorkerPool(ResourceProvider* resource_provider,
                               ContextProvider* context_provider,
                               size_t max_transfer_buffer_usage_bytes);
 
@@ skipping 34 matching lines @@
   bool raster_finished_task_pending_;
   bool raster_required_for_activation_finished_task_pending_;
   ResourceFormat format_;
 
   DISALLOW_COPY_AND_ASSIGN(PixelBufferRasterWorkerPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PIXEL_BUFFER_RASTER_WORKER_POOL_H_