cc: Simplify task and its derived classes.

cc/raster/one_copy_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/one_copy_tile_task_worker_pool.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <limits>
@@ skipping 254 matching lines @@
 
   task_graph_runner_->ScheduleTasks(namespace_token_, graph);
 }
 
 void OneCopyTileTaskWorkerPool::CheckForCompletedTasks() {
   TRACE_EVENT0("cc", "OneCopyTileTaskWorkerPool::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 OneCopyTileTaskWorkerPool::GetResourceFormat(
     bool must_support_alpha) const {
@@ skipping 448 matching lines @@
         return;
 
       busy_buffers_.front()->DestroyGLResources(gl);
       RemoveStagingBuffer(busy_buffers_.front().get());
       busy_buffers_.pop_front();
     }
   }
 }
 
 }  // namespace cc