mash: Cleanup ash shelf application menu code.

ash/common/shelf/shelf_application_menu_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 ASH_COMMON_SHELF_SHELF_APPLICATION_MENU_MODEL_H_
+#define ASH_COMMON_SHELF_SHELF_APPLICATION_MENU_MODEL_H_
+
+#include <memory>
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "ash/public/cpp/shelf_application_menu_item.h"
+#include "base/macros.h"
+#include "ui/base/models/simple_menu_model.h"
+
+class ShelfApplicationMenuModelTestAPI;
+
+namespace ash {
+
+// A menu model listing open applications associated with a shelf item.

[James Cook, 2017/02/06 17:30:21]

optional: A little piece of ASCII art showing what a menu looks like would make
it more obvious what the expected behavior is.

[msw, 2017/02/07 09:12:00]

Done.

+class ASH_EXPORT ShelfApplicationMenuModel
+    : public ui::SimpleMenuModel,
+      public ui::SimpleMenuModel::Delegate {
+ public:
+  // Makes a menu with a |title|, separators, and the specified |items|.
+  ShelfApplicationMenuModel(const base::string16& title,
+                            ShelfApplicationMenuItems items);
+  ~ShelfApplicationMenuModel() override;
+
+  // ui::SimpleMenuModel::Delegate:
+  bool IsCommandIdChecked(int command_id) const override;
+  bool IsCommandIdEnabled(int command_id) const override;
+  void ExecuteCommand(int command_id, int event_flags) override;
+
+ private:
+  friend class ShelfApplicationMenuModelTestAPI;
+
+  // Records UMA metrics when a menu item is selected.
+  void RecordMenuItemSelectedMetrics(int command_id,
+                                     int num_menu_items_enabled);
+
+  // The list of menu items as returned from the shelf item's controller.
+  ShelfApplicationMenuItems items_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShelfApplicationMenuModel);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SHELF_SHELF_APPLICATION_MENU_MODEL_H_