[Payments] Desktop: Error message in the dialog.

components/payments/content/payment_request.cc

Index: components/payments/content/payment_request.cc
diff --git a/components/payments/content/payment_request.cc b/components/payments/content/payment_request.cc
index ed48db057bf30588400e06c8a5f6d8b336445309..b34232b4ca25d89a6549aba13b7fb52ab85e1199 100644
--- a/components/payments/content/payment_request.cc
+++ b/components/payments/content/payment_request.cc
@@ -74,15 +74,17 @@ void PaymentRequest::Abort() {
     client_->OnAbort(true /* aborted_successfully */);
 }
 
-void PaymentRequest::Complete(payments::mojom::PaymentComplete result) {
+void PaymentRequest::Complete(mojom::PaymentComplete result) {
   if (!client_.is_bound())
     return;
 
-  // TODO(mathp): Validate |result|.
-
-  // When the renderer closes the connection,
-  // PaymentRequest::OnConnectionTerminated will be called.
-  client_->OnComplete();
+  if (result != mojom::PaymentComplete::SUCCESS) {
+    delegate_->ShowErrorMessage();
+  } else {
+    // When the renderer closes the connection,
+    // PaymentRequest::OnConnectionTerminated will be called.
+    client_->OnComplete();
+  }
 }
 
 void PaymentRequest::CanMakePayment() {