chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/file_system_provider/fileapi/provider_async_file_util.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_PROVIDER_ASYNC_FILE_UTIL_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_PROVIDER_ASYNC_FILE_UTIL_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "storage/browser/fileapi/async_file_util.h"
 
 namespace chromeos {
 namespace file_system_provider {
 
-class FileSystemInterface;
-
 // TODO(mtomasz): Remove this namespace.
 namespace internal {
 
 // The implementation of storage::AsyncFileUtil for provided file systems. It is
 // created one per Chrome process. It is responsible for routing calls to the
 // correct profile, and then to the correct profided file system.
 //
 // This class should be called AsyncFileUtil, without the Provided prefix. This
 // is impossible, though because of GYP limitations. There must not be two files
 // with the same name in a Chromium tree.
@@ skipping 74 matching lines @@
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ProviderAsyncFileUtil);
 };
 
 }  // namespace internal
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_FILEAPI_PROVIDER_ASYNC_FILE_UTIL_H_