[SyncFS] Migrate version management from MDDB to index classes

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 <string>
 
 #include "base/bind.h"
@@ skipping 12 matching lines @@
 }
 
 namespace leveldb {
 class DB;
 class WriteBatch;
 }
 
 namespace sync_file_system {
 namespace drive_backend {
 
+void PutVersionToBatch(int64 version, leveldb::WriteBatch* batch);
+
 void PutServiceMetadataToBatch(const ServiceMetadata& service_metadata,
                                leveldb::WriteBatch* batch);
 void PutFileMetadataToBatch(const FileMetadata& file,
                             leveldb::WriteBatch* batch);
 void PutFileTrackerToBatch(const FileTracker& tracker,
                            leveldb::WriteBatch* batch);
 
 void PutFileMetadataDeletionToBatch(const std::string& file_id,
                                     leveldb::WriteBatch* batch);
 void PutFileTrackerDeletionToBatch(int64 tracker_id,
@@ skipping 41 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_