private async void Button_Click_1(object sender, RoutedEventArgs e)
{
Windows.Web.Http.HttpClient client = new Windows.Web.Http.HttpClient();
IInputStream inputStream = await client.GetInputStreamAsync(new Uri(txtUrl.Text, UriKind.Absolute));
Stream webStream = inputStream.AsStreamForRead();
FileSavePicker picker = new FileSavePicker();
picker.FileTypeChoices.Add("Text", new List <string>()
{
".txt", ".html"
});
picker.FileTypeChoices.Add("Binary", new List <string>()
{
".txt", ".dat"
});
StorageFile file = await picker.PickSaveFileAsync();
Stream fileStream = await file.OpenStreamForWriteAsync();
await webStream.CopyToAsync(fileStream);
await new MessageDialog("File Saved").ShowAsync();
}