cc: Merge TileTaskRunner to TileTaskWorkerPool.

cc/raster/gpu_tile_task_worker_pool.cc

 // 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.
 
 #include "cc/raster/gpu_tile_task_worker_pool.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 
@@ skipping 102 matching lines @@
       namespace_token_(task_graph_runner_->GetNamespaceToken()),
       rasterizer_(new GpuRasterizer(context_provider,
                                     resource_provider,
                                     use_distance_field_text,
                                     gpu_rasterization_msaa_sample_count)) {}
 
 GpuTileTaskWorkerPool::~GpuTileTaskWorkerPool() {
   DCHECK_EQ(0u, completed_tasks_.size());
 }
 
-TileTaskRunner* GpuTileTaskWorkerPool::AsTileTaskRunner() {
-  return this;
-}
-
 void GpuTileTaskWorkerPool::Shutdown() {
   TRACE_EVENT0("cc", "GpuTileTaskWorkerPool::Shutdown");
 
   TaskGraph empty;
   task_graph_runner_->ScheduleTasks(namespace_token_, &empty);
   task_graph_runner_->WaitForTasksToFinishRunning(namespace_token_);
 }
 
 void GpuTileTaskWorkerPool::ScheduleTasks(TaskGraph* graph) {
   TRACE_EVENT0("cc", "GpuTileTaskWorkerPool::ScheduleTasks");
@@ skipping 52 matching lines @@
   return std::unique_ptr<RasterBuffer>(new RasterBufferImpl(
       rasterizer_.get(), resource, resource_content_id, previous_content_id));
 }
 
 void GpuTileTaskWorkerPool::ReleaseBufferForRaster(
     std::unique_ptr<RasterBuffer> buffer) {
   // Nothing to do here. RasterBufferImpl destructor cleans up after itself.
 }
 
 }  // namespace cc