storage: Cleanup class/struct forward declarations

storage/browser/quota/quota_task.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 STORAGE_BROWSER_QUOTA_QUOTA_TASK_H_
 #define STORAGE_BROWSER_QUOTA_QUOTA_TASK_H_
 
 #include <set>
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "storage/browser/storage_browser_export.h"
 
 namespace base {
 class SingleThreadTaskRunner;
-class TaskRunner;
 }
 
 namespace storage {
 
 class QuotaTaskObserver;
 
 // A base class for quota tasks.
 // TODO(kinuko): Revise this using base::Callback.
 class QuotaTask {
  public:
@@ skipping 41 matching lines @@
 
   void RegisterTask(QuotaTask* task);
   void UnregisterTask(QuotaTask* task);
 
   typedef std::set<QuotaTask*> TaskSet;
   TaskSet running_quota_tasks_;
 };
 }
 
 #endif  // STORAGE_BROWSER_QUOTA_QUOTA_TASK_H_