cc: Simplify task and its derived classes.

cc/raster/zero_copy_tile_task_worker_pool.cc

 // 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.
 
 #include "cc/raster/zero_copy_tile_task_worker_pool.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 
@@ skipping 94 matching lines @@
 
   ScheduleTasksOnOriginThread(this, graph);
   task_graph_runner_->ScheduleTasks(namespace_token_, graph);
 }
 
 void ZeroCopyTileTaskWorkerPool::CheckForCompletedTasks() {
   TRACE_EVENT0("cc", "ZeroCopyTileTaskWorkerPool::CheckForCompletedTasks");
 
   task_graph_runner_->CollectCompletedTasks(namespace_token_,
                                             &completed_tasks_);
-  for (Task::Vector::const_iterator it = completed_tasks_.begin();
+  for (DependencyTask::Vector::const_iterator it = completed_tasks_.begin();
        it != completed_tasks_.end(); ++it) {
-    TileTask* task = static_cast<TileTask*>(it->get());
+    DependencyTask* task = static_cast<DependencyTask*>(it->get());
 
     task->WillComplete();
     task->CompleteOnOriginThread(this);
     task->DidComplete();
   }
   completed_tasks_.clear();
 }
 
 ResourceFormat ZeroCopyTileTaskWorkerPool::GetResourceFormat(
     bool must_support_alpha) const {
@@ skipping 18 matching lines @@
   return make_scoped_ptr<RasterBuffer>(
       new RasterBufferImpl(resource_provider_, resource));
 }
 
 void ZeroCopyTileTaskWorkerPool::ReleaseBufferForRaster(
     scoped_ptr<RasterBuffer> buffer) {
   // Nothing to do here. RasterBufferImpl destructor cleans up after itself.
 }
 
 }  // namespace cc