storage: Cleanup class/struct forward declarations

storage/browser/fileapi/sandbox_file_system_backend_delegate.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_FILEAPI_SANDBOX_FILE_SYSTEM_BACKEND_DELEGATE_H_
 #define STORAGE_BROWSER_FILEAPI_SANDBOX_FILE_SYSTEM_BACKEND_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 35 matching lines @@
 namespace storage {
 
 class AsyncFileUtil;
 class FileStreamWriter;
 class FileSystemFileUtil;
 class FileSystemOperationContext;
 class FileSystemURL;
 class FileSystemUsageCache;
 class ObfuscatedFileUtil;
 class QuotaReservationManager;
-class SandboxFileSystemBackend;
 class SandboxQuotaObserver;
 
 // Delegate implementation of the some methods in Sandbox/SyncFileSystemBackend.
 // An instance of this class is created and owned by FileSystemContext.
 class STORAGE_EXPORT SandboxFileSystemBackendDelegate
     : public FileSystemQuotaUtil {
  public:
   typedef FileSystemBackend::OpenFileSystemCallback OpenFileSystemCallback;
 
   // The FileSystem directory name.
@@ skipping 191 matching lines @@
   base::Time next_release_time_for_open_filesystem_stat_;
 
   base::WeakPtrFactory<SandboxFileSystemBackendDelegate> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SandboxFileSystemBackendDelegate);
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_FILEAPI_SANDBOX_FILE_SYSTEM_BACKEND_DELEGATE_H_