[Sync] Replace typedef with using.

components/sync/base/progress_marker_map.h

 // Copyright 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.
 
 #ifndef COMPONENTS_SYNC_BASE_PROGRESS_MARKER_MAP_H_
 #define COMPONENTS_SYNC_BASE_PROGRESS_MARKER_MAP_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "components/sync/base/model_type.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace syncer {
 
 // A container that maps ModelType to serialized
 // DataTypeProgressMarkers.
-typedef std::map<ModelType, std::string> ProgressMarkerMap;
+using ProgressMarkerMap = std::map<ModelType, std::string>;
 
 std::unique_ptr<base::DictionaryValue> ProgressMarkerMapToValue(
     const ProgressMarkerMap& marker_map);
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_BASE_PROGRESS_MARKER_MAP_H_