protected virtual void OnRestoreFailed(InAppPurchaseException ex)
 {
     if (RestoreFailed != null)
     {
         RestoreFailed(ex);
     }
 }
 protected override void OnRestoreFailed(InAppPurchaseException ex)
 {
     UIApplication.SharedApplication.InvokeOnMainThread(delegate
     {
         base.OnRestoreFailed(ex);
     });
 }
 protected virtual void OnPurchaseFailed(InAppPurchaseException ex)
 {
     if (PurchaseFailed != null)
     {
         PurchaseFailed(ex);
     }
 }