[Payments] Add combobox support to editors.

chrome/browser/ui/views/payments/validating_textfield.cc

 // 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.
 
 #include "chrome/browser/ui/views/payments/validating_textfield.h"
 
 #include <utility>
 
 namespace payments {
 
 ValidatingTextfield::ValidatingTextfield(
-    std::unique_ptr<ValidatingTextfield::Delegate> delegate)
+    std::unique_ptr<ValidationDelegate> delegate)
     : Textfield(), delegate_(std::move(delegate)) {}
 
 ValidatingTextfield::~ValidatingTextfield() {}
 
 void ValidatingTextfield::OnBlur() {
   Textfield::OnBlur();
 
   // The first validation should be on a blur. The subsequent validations will
   // occur when the content changes.
   if (!was_validated_) {
@@ skipping 10 matching lines @@
 
   Validate();
 }
 
 void ValidatingTextfield::Validate() {
   // ValidateTextfield may have side-effects, such as displaying errors.
   SetInvalid(!delegate_->ValidateTextfield(this));
 }
 
 }  // namespace payments