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

components/sync_driver/local_device_info_provider_mock.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_DRIVER_LOCAL_DEVICE_INFO_PROVIDER_MOCK_H_
 #define COMPONENTS_SYNC_DRIVER_LOCAL_DEVICE_INFO_PROVIDER_MOCK_H_
 
+#include <string>
+
 #include "components/sync_driver/device_info.h"
 #include "components/sync_driver/local_device_info_provider.h"
 
 namespace sync_driver {
 
 class LocalDeviceInfoProviderMock
     : public sync_driver::LocalDeviceInfoProvider {
  public:
   // Creates uninitialized provider.
   LocalDeviceInfoProviderMock();
@@ skipping 20 matching lines @@
  private:
   bool is_initialized_;
 
   scoped_ptr<DeviceInfo> local_device_info_;
   base::CallbackList<void(void)> callback_list_;
 };
 
 }  // namespace sync_driver
 
 #endif  // COMPONENTS_SYNC_DRIVER_LOCAL_DEVICE_INFO_PROVIDER_MOCK_H_