private void OnStart()
{
IsStarted = true;
_grabber = ServiceLocator.Current.GetInstance <IGrabber>(SelectedSource.TypeName);
_grabber.ProgressReport += GrabberOnProgressReport;
_grabber.ProgressChanged += GrabberOnProgressChanged;
_grabber.GrabbingFinished += GrabberOnGrabbingFinished;
_grabber.StartAsync(new DirectoryCheckStrategy(_cacheFilePaths));
}