[Payment Request] Refactors edit view controller

ios/showcase/payments/sc_payments_editor_coordinator.mm

 // 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.
 
 #import "ios/showcase/payments/sc_payments_editor_coordinator.h"
 
 #import "base/mac/foundation_util.h"
 #include "base/strings/utf_string_conversions.h"
 #import "ios/chrome/browser/ui/autofill/autofill_ui_type.h"
 #import "ios/chrome/browser/ui/autofill/autofill_ui_type_util.h"
@@ skipping 84 matching lines @@
 #pragma mark - PaymentRequestEditViewControllerDataSource
 
 - (CollectionViewItem*)headerItem {
   return nil;
 }
 
 - (BOOL)shouldHideBackgroundForHeaderItem {
   return NO;
 }
 
+- (UIImage*)iconIdentifyingEditorField:(EditorField*)field {
+  return nil;
+}
+
 #pragma mark - PaymentRequestEditViewControllerValidator
 
 - (NSString*)paymentRequestEditViewController:
                  (PaymentRequestEditViewController*)controller
                                 validateField:(EditorField*)field {
   if (field.value.length)
     return nil;
   else if (field.isRequired)
     return @"Field is required";
   else
     return nil;
 }
 
 @end