mash: Remove shelf app menu item objects.

ash/common/shelf/app_list_shelf_item_delegate.cc

 // Copyright 2013 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 "ash/common/shelf/app_list_shelf_item_delegate.h"
 
 #include "ash/common/shelf/shelf_model.h"
 #include "ash/common/strings/grit/ash_strings.h"
 #include "ash/common/wm_shell.h"
 #include "base/memory/ptr_util.h"
@@ skipping 24 matching lines @@
 ShelfAction AppListShelfItemDelegate::ItemSelected(ui::EventType event_type,
                                                    int event_flags,
                                                    int64_t display_id,
                                                    ShelfLaunchSource source) {
   WmShell::Get()->ToggleAppList();
   return SHELF_ACTION_APP_LIST_SHOWN;
 }
 
 ShelfAppMenuItemList AppListShelfItemDelegate::GetAppMenuItems(
     int event_flags) {
-  // AppList does not show an application menu.
+  // Return an empty item list to avoid showing an application menu.
   return ShelfAppMenuItemList();
 }
 
+void AppListShelfItemDelegate::ExecuteCommand(uint32_t command_id,
+                                              int event_flags) {
+  // This delegate does not support showing an application menu.
+  NOTIMPLEMENTED();
+}
+
 void AppListShelfItemDelegate::Close() {}
 
 }  // namespace ash