public static void GetToastUri(Action<Uri> callback)
{
var channel = HttpNotificationChannel.Find(ChannelName);
if (channel == null) {
channel = new HttpNotificationChannel(ChannelName);
channel.RegisterEvents(callback);
channel.Open();
channel.BindToShellToast();
} else {
channel.RegisterEvents(callback);
}
callback(channel.ChannelUri);
}