[Payments] Display the shipping option error alongside the address

components/payments/content/payment_request_spec.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_PAYMENTS_CONTENT_PAYMENT_REQUEST_SPEC_H_
 #define COMPONENTS_PAYMENTS_CONTENT_PAYMENT_REQUEST_SPEC_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 76 matching lines @@
   base::string16 GetFormattedCurrencyAmount(const std::string& amount);
 
   // Uses CurrencyFormatter to get the formatted currency code for this
   // request's currency. Will use currency of the "total" display item, because
   // all items are supposed to have the same currency in a given request.
   std::string GetFormattedCurrencyCode();
 
   mojom::PaymentShippingOption* selected_shipping_option() const {
     return selected_shipping_option_;
   }
+  // if |selected_shipping_option()| is nullptr, this may contain a non-empty
+  // error returned by the merchant.
+  const std::string& selected_shipping_option_error() const {
+    return selected_shipping_option_error_;
+  }
 
   const mojom::PaymentDetails& details() const { return *details_.get(); }
 
   void StartWaitingForUpdateWith(UpdateReason reason);
 
  private:
   friend class PaymentRequestDialogView;
   void add_observer_for_testing(Observer* observer_for_testing) {
     observer_for_testing_ = observer_for_testing;
   }
@@ skipping 18 matching lines @@
   CurrencyFormatter* GetOrCreateCurrencyFormatter(
       const std::string& currency_code,
       const std::string& currency_system,
       const std::string& locale_name);
 
   mojom::PaymentOptionsPtr options_;
   mojom::PaymentDetailsPtr details_;
   const std::string app_locale_;
   // The currently shipping option as specified by the merchant.
   mojom::PaymentShippingOption* selected_shipping_option_;
+  std::string selected_shipping_option_error_;
 
   std::unique_ptr<CurrencyFormatter> currency_formatter_;
 
   // A list/set of supported basic card networks. The list is used to keep the
   // order in which they were specified by the merchant. The set is used for
   // fast lookup of supported methods.
   std::vector<std::string> supported_card_networks_;
   std::set<std::string> supported_card_networks_set_;
 
   // Only the set of basic-card specified networks. NOTE: callers should use
   // |supported_card_networks_set_| to check merchant support.
   std::set<std::string> basic_card_specified_networks_;
 
   // The |observer_for_testing_| will fire after all the |observers_| have been
   // notified.
   base::ObserverList<Observer> observers_;
   Observer* observer_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(PaymentRequestSpec);
 };
 
 }  // namespace payments
 
 #endif  // COMPONENTS_PAYMENTS_CONTENT_PAYMENT_REQUEST_SPEC_H_