[Merge M60][Payments] Refactor the year and month combobox models and preselect.

chrome/browser/ui/views/payments/preselected_combobox_model.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_PRESELECTED_COMBOBOX_MODEL_H_
-#define CHROME_BROWSER_UI_VIEWS_PAYMENTS_PRESELECTED_COMBOBOX_MODEL_H_
-
-#include <vector>
-
-#include "base/macros.h"
-#include "base/strings/string16.h"
-#include "ui/base/models/simple_combobox_model.h"
-
-namespace payments {
-
-// A simple data model for a combobox that takes a string16 vector as the items,
-// as well as the default selected index. An empty string is a separator.
-class PreselectedComboboxModel : public ui::SimpleComboboxModel {
- public:
-  PreselectedComboboxModel(const std::vector<base::string16>& items,
-                           int default_index);
-  ~PreselectedComboboxModel() override;
-
-  // ui::ComboboxModel:
-  int GetDefaultIndex() const override;
-
- private:
-  const int default_index_;
-
-  DISALLOW_COPY_AND_ASSIGN(PreselectedComboboxModel);
-};
-
-}  // namespace payments
-
-#endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PRESELECTED_COMBOBOX_MODEL_H_