public static void onLaunchWebAuthFlowCallback(string responseUrl, int callbackId)
        {
            launchWebAuthFlowCallback callback = CallbackRegisrty.GetCallback <launchWebAuthFlowCallback> (callbackId);

            if (callback != null)
            {
                callback(responseUrl, callbackId);
            }
        }
 public static extern string LaunchWebAuthFlow(string url, bool interactive, launchWebAuthFlowCallback callback, int callbackId);