public partial class HomeView : PhoneApplicationPage
{
    public HomeView()
    {
        InitializeComponent();
        Loaded += HomeView_Loaded;
    }

    private void HomeView_Loaded(object sender, RoutedEventArgs e)
    {
        UserAgentHelper.GetUserAgent(
            LayoutRoot,
            userAgent =>
                {
                    // TODO: Store this wherever you want
                    ApplicationSettings.Current.UserAgent = userAgent;
                });
    }
}