Add simple mash context menu support.

ash/mus/context_menu_mus.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 2016 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_SHELL_CONTEXT_MENU_H_
-#define ASH_SHELL_CONTEXT_MENU_H_
+#ifndef ASH_MUS_CONTEXT_MENU_MUS_H_
+#define ASH_MUS_CONTEXT_MENU_MUS_H_
 
 #include "ash/shelf/shelf_alignment_menu.h"
 #include "base/macros.h"
 #include "ui/base/models/simple_menu_model.h"
 
 namespace ash {
 
 class Shelf;
 
-namespace shell {
-
-// Context menu for the ash shell.
-class ContextMenu : public ui::SimpleMenuModel,
-                    public ui::SimpleMenuModel::Delegate {
+// Context menu for mash.
+// TODO(msw): Mimic logic in LauncherContextMenu.
+class ContextMenuMus : public ui::SimpleMenuModel,
+                       public ui::SimpleMenuModel::Delegate {
  public:
-  explicit ContextMenu(Shelf* shelf);
-  ~ContextMenu() override;
+  explicit ContextMenuMus(Shelf* shelf);
+  ~ContextMenuMus() override;
 
   // ui::SimpleMenuModel::Delegate overrides:
   bool IsCommandIdChecked(int command_id) const override;
   bool IsCommandIdEnabled(int command_id) const override;
   bool GetAcceleratorForCommandId(int command_id,
                                   ui::Accelerator* accelerator) override;
   void ExecuteCommand(int command_id, int event_flags) override;
 
  private:
   enum MenuItem {
     MENU_AUTO_HIDE,
     MENU_ALIGNMENT_MENU,
+    MENU_CHANGE_WALLPAPER,
   };
 
   Shelf* shelf_;
   ShelfAlignmentMenu alignment_menu_;
 
-  DISALLOW_COPY_AND_ASSIGN(ContextMenu);
+  DISALLOW_COPY_AND_ASSIGN(ContextMenuMus);
 };
 
-}  // namespace shell
 }  // namespace ash
 
-#endif  // ASH_SHELL_CONTEXT_MENU_H_
+#endif  // ASH_MUS_CONTEXT_MENU_MUS_H_