/// <summary>
    /// Callback used when device is successfully registered with GCM. Sends data do PlayFab.
    /// </summary>
    /// <param name="registrationID">Registration ID.</param>
    void OnDeviceRegistered(string registrationID)
    {
        GCM.SetNotificationsEnabled(true);

        AndroidDevicePushNotificationRegistrationRequest request = new AndroidDevicePushNotificationRegistrationRequest();

        request.DeviceToken = registrationID;
        request.SendPushNotificationConfirmation = true;

        PlayFabClientAPI.AndroidDevicePushNotificationRegistration(request, OnRegisteredForPushNotification, OnRegisterForPushNotificationError);
    }