cc: Add TaskGraphRunner sub-namespaces with task concurrency limits.

cc/resources/gpu_tile_task_worker_pool.h

 // Copyright 2014 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_GPU_TILE_TASK_WORKER_POOL_H_
 #define CC_RESOURCES_GPU_TILE_TASK_WORKER_POOL_H_
 
 #include "base/memory/weak_ptr.h"
 #include "cc/resources/tile_task_runner.h"
 #include "cc/resources/tile_task_worker_pool.h"
@@ skipping 21 matching lines @@
   void ScheduleTasks(TileTaskQueue* queue) override;
   void CheckForCompletedTasks() override;
   ResourceFormat GetResourceFormat() override;
 
   // Overridden from TileTaskClient:
   scoped_ptr<RasterBuffer> AcquireBufferForRaster(
       const Resource* resource) override;
   void ReleaseBufferForRaster(scoped_ptr<RasterBuffer> buffer) override;
 
  private:
+  static const int kGpuSubNamespace = 1;
+  static const int kGpuMaxConcurrentTasks = 1;
+
   GpuTileTaskWorkerPool(base::SequencedTaskRunner* task_runner,
                         TaskGraphRunner* task_graph_runner,
                         GpuRasterizer* rasterizer);
 
   void OnTaskSetFinished(TaskSet task_set);
   void CompleteTasks(const Task::Vector& tasks);
 
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   TaskGraphRunner* task_graph_runner_;
   const NamespaceToken namespace_token_;
@@ skipping 13 matching lines @@
       task_set_finished_weak_ptr_factory_;
 
   base::WeakPtrFactory<GpuTileTaskWorkerPool> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuTileTaskWorkerPool);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_GPU_TILE_TASK_WORKER_POOL_H_