storage: Cleanup class/struct forward declarations

storage/browser/fileapi/file_system_quota_util.h

 // Copyright (c) 2012 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_FILEAPI_FILE_SYSTEM_QUOTA_UTIL_H_
 #define STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_QUOTA_UTIL_H_
 
 #include <stdint.h>
 
 #include <set>
 #include <string>
 
 #include "base/files/file.h"
 #include "storage/browser/storage_browser_export.h"
 #include "storage/common/fileapi/file_system_types.h"
 #include "url/gurl.h"
 
-namespace base {
-class SequencedTaskRunner;
-}
-
 namespace storage {
 class QuotaManagerProxy;
 }
 
 namespace storage {
 
 class FileSystemContext;
 class QuotaReservation;
 
 // An abstract interface that provides common quota-related utility functions
@@ skipping 28 matching lines @@
   // Creates new reservation object for the origin and the type.
   virtual scoped_refptr<QuotaReservation>
       CreateQuotaReservationOnFileTaskRunner(
           const GURL& origin_url,
           FileSystemType type) = 0;
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_FILEAPI_FILE_SYSTEM_QUOTA_UTIL_H_