SyncFS: Factor out DriveMetadataDB migration functions

chrome/browser/sync_file_system/drive/metadata_db_migration_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_METADATA_DB_MIGRATION_UTIL_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_METADATA_DB_MIGRATION_UTIL_H_
 
 #include <string>
 
 #include "chrome/browser/sync_file_system/sync_file_system.pb.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 #include "webkit/browser/fileapi/syncable/sync_status_code.h"
 
+class GURL;
+
 namespace sync_file_system {
 namespace drive {
 
+// Parses a filesystem URL which contains 'drive' as a service name
+// (a.k.a. V0-format filesystem URL).
+//
+// When you parse V0-format filesystem URL, you should use this function instead
+// of DeserializeSyncableFileSystemURL() since 'drive' service name is no longer
+// used and the deserializer cannot parse the unregistered service name.
+//
+// EXAMPLE:
+// Assume following argument is given.
+//   url: 'filesystem:http://www.example.com/external/drive/foo/bar'
+// returns
+//   origin: 'http://www.example.com/'
+//   path:   'foo/bar'
+bool ParseV0FormatFileSystemURL(const GURL& url,
+                                GURL* origin,
+                                base::FilePath* path);
+
 // Adds "file:" prefix to WAPI resource ID.
 // EXAMPLE:  "xxx" => "file:xxx"
 std::string AddWapiFilePrefix(const std::string& resource_id);
 
 // Adds "folder:" prefix to WAPI resource ID.
 // EXAMPLE:  "xxx" => "folder:xxx"
 std::string AddWapiFolderPrefix(const std::string& resource_id);
 
 // Adds a prefix corresponding to the given |type|.
 std::string AddWapiIdPrefix(const std::string& resource_id,
                             DriveMetadata_ResourceType type);
 
 // Removes a prefix from WAPI resource ID.
 // EXAMPLE:
 //   "file:xxx"    =>  "xxx"
 //   "folder:yyy"  =>  "yyy"
 //   "zzz"         =>  "zzz"
 std::string RemoveWapiIdPrefix(const std::string& resource_id);
 
-// Migrate |db| scheme from version 1 to version 2.
+// Migrate |db| schema from version 0 to version 1.
+SyncStatusCode MigrateDatabaseFromV0ToV1(leveldb::DB* db);
+
+// Migrate |db| schema from version 1 to version 2.
 SyncStatusCode MigrateDatabaseFromV1ToV2(leveldb::DB* db);
 
 }  // namespace drive
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_METADATA_DB_MIGRATION_UTIL_H_