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

ash/common/shelf/shelf_item_delegate.cc

Index: ash/common/shelf/shelf_item_delegate.cc
diff --git a/ash/common/shelf/shelf_item_delegate.cc b/ash/common/shelf/shelf_item_delegate.cc
index bc3ec8c37d451c058c20cdf8d031306edb4f6cf8..7484d04e6d1d564e37ec8823dd7e1a813527789c 100644
--- a/ash/common/shelf/shelf_item_delegate.cc
+++ b/ash/common/shelf/shelf_item_delegate.cc
@@ -8,12 +8,19 @@
 
 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