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

components/sync_driver/invalidation_helper.cc

 // Copyright 2014 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 "components/sync_driver/invalidation_helper.h"
 
+#include <string>
+
 #include "google/cacheinvalidation/types.pb.h"
 
 namespace syncer {
 
 bool RealModelTypeToObjectId(ModelType model_type,
                              invalidation::ObjectId* object_id) {
   std::string notification_type;
   if (!RealModelTypeToNotificationType(model_type, &notification_type)) {
     return false;
   }
   object_id->Init(ipc::invalidation::ObjectSource::CHROME_SYNC,
                   notification_type);
   return true;
 }
 
 ObjectIdSet ModelTypeSetToObjectIdSet(ModelTypeSet model_types) {
   ObjectIdSet ids;
   for (ModelTypeSet::Iterator it = model_types.First(); it.Good(); it.Inc()) {
     invalidation::ObjectId model_type_as_id;
     if (!RealModelTypeToObjectId(it.Get(), &model_type_as_id)) {
       DLOG(WARNING) << "Invalid model type " << it.Get();
       continue;
     }
     ids.insert(model_type_as_id);
   }
   return ids;
 }
 
 }  // namespace syncer