public void Start(MvxGeoLocationOptions options, Action<MvxGeoLocation> success, Action<MvxLocationError> error)
        {
            lock (this)
            {
                _locationCallback = success;
                _errorCallback = error;

                PlatformSpecificStart(options);
            }
        }
 protected abstract void PlatformSpecificStart(MvxGeoLocationOptions options);