mash: Use mojo for ShelfItemDelegate and [app] MenuItem.

ash/common/shelf/shelf_item_delegate.cc

 // 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.
 
 #include "ash/common/shelf/shelf_item_delegate.h"
 
 #include "ui/display/types/display_constants.h"
 
 namespace ash {
 
+namespace {
+
+// A callback that does nothing after shelf item selection handling.
+void NoopCallback(ShelfAction, ShelfItemDelegate::MenuItemList) {}
+
+}  // namespace
+
 ShelfItemDelegate::ShelfItemDelegate() {}
 ShelfItemDelegate::~ShelfItemDelegate() {}
 
-ShelfAction ShelfItemDelegate::ItemSelectedBySource(ShelfLaunchSource source) {
-  return ItemSelected(ui::ET_UNKNOWN, ui::EF_NONE, display::kInvalidDisplayId,
-                      source);
+void ShelfItemDelegate::ItemSelectedBySource(ShelfLaunchSource source) {
+  ItemSelected(nullptr, display::kInvalidDisplayId, source,
+               base::Bind(&NoopCallback));
 }
 
 }  // namespace ash