SyncFS: Add resource type field into DriveMetadata

chrome/browser/sync_file_system/sync_file_system.proto

 // Copyright (c) 2012 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.
 //
 // Protocol buffer definitions for Syncable FileSystem.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package sync_file_system;
 
 message DriveMetadata {
   required string resource_id = 1;
   required string md5_checksum = 2;
   required bool conflicted = 3;
 
   // When true, indicates that the remote file identified by |resource_id|
   // should be fetched for solving the conflict (resolve-to-remote resolution).
   required bool to_be_fetched = 4;
+
+  enum ResourceType {
+    RESOURCE_TYPE_FILE = 0;
+    RESOURCE_TYPE_FOLDER = 1;
+  }
+
+  optional ResourceType type = 5 [default = RESOURCE_TYPE_FILE];
 }