[Sync] Fixing sync_driver lint violations and adding PRESUBMIT lint check.

components/sync_driver/backend_migrator.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_DRIVER_BACKEND_MIGRATOR_H_
 #define COMPONENTS_SYNC_DRIVER_BACKEND_MIGRATOR_H_
 
+#include <string>
+
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "components/sync_driver/data_type_manager.h"
 #include "sync/internal_api/public/base/model_type.h"
 
 namespace syncer {
 struct UserShare;
 }  // namespace syncer
 
@@ skipping 83 matching lines @@
   base::Closure migration_done_callback_;
 
   base::WeakPtrFactory<BackendMigrator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackendMigrator);
 };
 
 }  // namespace browser_sync
 
 #endif  // COMPONENTS_SYNC_DRIVER_BACKEND_MIGRATOR_H_