mash: Remove shelf app menu item objects.

ash/common/shelf/app_list_shelf_item_delegate.cc

Index: ash/common/shelf/app_list_shelf_item_delegate.cc
diff --git a/ash/common/shelf/app_list_shelf_item_delegate.cc b/ash/common/shelf/app_list_shelf_item_delegate.cc
index 2c04383cdd84c08d41457e9e45b85cefce619936..398b3cb2e530807e668a37f24d17cce98f6eb763 100644
--- a/ash/common/shelf/app_list_shelf_item_delegate.cc
+++ b/ash/common/shelf/app_list_shelf_item_delegate.cc
@@ -42,10 +42,16 @@ ShelfAction AppListShelfItemDelegate::ItemSelected(ui::EventType event_type,
 
 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