[Payments] Add error messages to credit card editor.

chrome/browser/ui/views/payments/payment_request_dialog_view_ids.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 CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_DIALOG_VIEW_IDS_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_DIALOG_VIEW_IDS_H_
 
+#include "components/autofill/core/browser/field_types.h"
+
 // This defines an enumeration of IDs that can uniquely identify a view within
 // the scope of the Payment Request Dialog.
 
 namespace payments {
 
 enum class DialogViewID : int {
-  VIEW_ID_NONE,
+  VIEW_ID_NONE = autofill::MAX_VALID_FIELD_TYPE,
 
   // The following are views::Button (clickable).
   PAYMENT_SHEET_CONTACT_INFO_SECTION,
   PAYMENT_SHEET_PAYMENT_METHOD_SECTION,
   PAYMENT_SHEET_SHIPPING_SECTION,
   PAYMENT_SHEET_SUMMARY_SECTION,
   PAYMENT_METHOD_ADD_CARD_BUTTON,
   EDITOR_SAVE_BUTTON,
 
   // The following are StyledLabel objects.
   ORDER_SUMMARY_TOTAL_AMOUNT_LABEL,
   ORDER_SUMMARY_LINE_ITEM_1,
   ORDER_SUMMARY_LINE_ITEM_2,
   ORDER_SUMMARY_LINE_ITEM_3,
+
+  // Used to label the error labels with an offset, which gets added to
+  // the Autofill type value they represent (for tests).
+  ERROR_LABEL_OFFSET,
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_DIALOG_VIEW_IDS_H_