[Payment Request] Error message screen

ios/chrome/browser/payments/payment_request_coordinator.mm

Index: ios/chrome/browser/payments/payment_request_coordinator.mm
diff --git a/ios/chrome/browser/payments/payment_request_coordinator.mm b/ios/chrome/browser/payments/payment_request_coordinator.mm
index 29e293a9ca46110765d440276b69522fe62729b4..d521e855aa240db35db6bac1c7763a562dc2b87d 100644
--- a/ios/chrome/browser/payments/payment_request_coordinator.mm
+++ b/ios/chrome/browser/payments/payment_request_coordinator.mm
@@ -22,11 +22,13 @@
 #include "components/autofill/core/browser/payments/full_card_request.h"
 #include "components/autofill/core/browser/personal_data_manager.h"
 #include "components/autofill/core/browser/ui/card_unmask_prompt_controller_impl.h"
+#include "components/strings/grit/components_strings.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/payments/payment_request.h"
 #include "ios/chrome/browser/payments/payment_request_util.h"
 #include "ios/chrome/browser/ui/autofill/card_unmask_prompt_view_bridge.h"
+#include "ui/base/l10n/l10n_util.h"
 
 // The unmask prompt UI for Payment Request.
 class PRCardUnmaskPromptViewBridge
@@ -119,6 +121,7 @@ class FullCardRequester
   base::WeakNSProtocol<id<PaymentRequestCoordinatorDelegate>> _delegate;
   base::scoped_nsobject<UINavigationController> _navigationController;
   base::scoped_nsobject<PaymentRequestViewController> _viewController;
+  base::scoped_nsobject<PaymentRequestErrorCoordinator> _errorCoordinator;
   base::scoped_nsobject<PaymentItemsDisplayCoordinator>
       _itemsDisplayCoordinator;
   base::scoped_nsobject<ShippingAddressSelectionCoordinator>
@@ -185,15 +188,14 @@ class FullCardRequester
 }
 
 - (void)stop {
-  [[_navigationController presentingViewController]
-      dismissViewControllerAnimated:YES
-                         completion:nil];
+  [_navigationController dismissViewControllerAnimated:YES completion:nil];
   _itemsDisplayCoordinator.reset();
   _shippingAddressSelectionCoordinator.reset();
   _shippingOptionSelectionCoordinator.reset();
   _methodSelectionCoordinator.reset();
-  _navigationController.reset();
+  _errorCoordinator.reset();
   _viewController.reset();
+  _navigationController.reset();
 }
 
 - (void)sendPaymentResponse {
@@ -273,6 +275,15 @@ class FullCardRequester
   }
 }
 
+- (void)displayErrorWithCallback:(void (^)())callback {
+  _errorCoordinator.reset([[PaymentRequestErrorCoordinator alloc]
+      initWithBaseViewController:_navigationController]);
+  [_errorCoordinator setCallback:callback];
+  [_errorCoordinator setDelegate:self];
+
+  [_errorCoordinator start];
+}
+
 #pragma mark - PaymentRequestViewControllerDelegate
 
 - (void)paymentRequestViewControllerDidCancel:
@@ -327,6 +338,19 @@ class FullCardRequester
   [_methodSelectionCoordinator start];
 }
 
+#pragma mark - PaymentRequestErrorCoordinatorDelegate
+
+- (void)paymentRequestErrorCoordinatorDidDismiss:
+    (PaymentRequestErrorCoordinator*)coordinator {
+  void (^callback)() = coordinator.callback;
+
+  [_errorCoordinator stop];
+  _errorCoordinator.reset();
+
+  if (callback)
+    callback();
+}
+
 #pragma mark - PaymentItemsDisplayCoordinatorDelegate
 
 - (void)paymentItemsDisplayCoordinatorDidReturn: