chrome: Cleanup class/struct forward declarations

chrome/browser/sync_file_system/drive_backend/drive_backend_util.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 CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_DRIVE_BACKEND_UTIL_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_DRIVE_BACKEND_UTIL_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
 #include "chrome/browser/sync_file_system/sync_status_code.h"
 #include "google_apis/drive/drive_api_error_codes.h"
 #include "storage/browser/blob/scoped_file.h"
 
-namespace google_apis {
-class ChangeResource;
-class FileResource;
-}
-
 namespace sync_file_system {
 namespace drive_backend {
 
 class LevelDBWrapper;
 
 void PutVersionToDB(int64_t version, LevelDBWrapper* db);
 
 void PutServiceMetadataToDB(const ServiceMetadata& service_metadata,
                             LevelDBWrapper* db);
 void PutFileMetadataToDB(const FileMetadata& file, LevelDBWrapper* db);
@@ skipping 45 matching lines @@
 base::Callback<R()> CreateComposedFunction(
     const base::Callback<T()>& g,
     const base::Callback<R(S)>& f) {
   return base::Bind(&ComposeFunction<R, S, T>, g, f);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_DRIVE_BACKEND_UTIL_H_