[SyncFS] Migrate version management from MDDB to index classes

chrome/browser/sync_file_system/drive_backend/drive_backend_util.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_util.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/browser/drive/drive_api_util.h"
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_constants.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
 #include "chrome/browser/sync_file_system/logger.h"
 #include "google_apis/drive/drive_api_parser.h"
 #include "google_apis/drive/gdata_wapi_parser.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 #include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
 
 namespace sync_file_system {
 namespace drive_backend {
 
+void PutVersionInfoToBatch(int64 version, leveldb::WriteBatch* batch) {
+  DCHECK(batch);

[tzik, 2014/07/16 04:35:27]

if (!batch)return; for consistency?

[peria, 2014/07/16 04:40:49]

Done.

+  batch->Put(kDatabaseVersionKey, base::Int64ToString(version));
+}
+
 void PutServiceMetadataToBatch(const ServiceMetadata& service_metadata,
                                leveldb::WriteBatch* batch) {
   if (!batch)
     return;
 
   std::string value;
   bool success = service_metadata.SerializeToString(&value);
   DCHECK(success);
   batch->Put(kServiceMetadataKey, value);
 }
@@ skipping 143 matching lines @@
 
   scoped_ptr<ServiceMetadata> service_metadata(new ServiceMetadata);
   if (!status.ok() || !service_metadata->ParseFromString(value))
     service_metadata->set_next_tracker_id(1);
 
   return service_metadata.Pass();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system