[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_
 
 // 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,
 
   // 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,
+
+  ERROR_LABEL_OFFSET = 1000,

[anthonyvd, 2017/02/22 19:32:45]

You can omit the 1000 here I think. It's guaranteed to be greater than all the
values above it so the general pattern is to just name it something that
indicates it should be the last element in the enum and add a comment to that
effect. What about DIALOG_VIEW_IDS_MAX?

[Mathieu, 2017/02/22 20:08:59]

You're right I can get rid of the 1000 here, I've set VIEW_ID_NONE to start at
the Autofill type's max. To explain a bit more, this is a slight hack that I'm
using. The input field will have set_id(field.type), (e.g. set_id(56)) and the
error label will have set_id(ERROR_LABEL_OFFSET + 56), so I can recall both
during tests. Here's the autofill types:
https://cs.chromium.org/chromium/src/components/autofill/core/browser/field_t...

Hey don't hate the player, hate the ViewID game!

 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_DIALOG_VIEW_IDS_H_