mash: Cleanup ash shelf application menu code.

ash/common/test/test_shelf_item_delegate.cc

Index: ash/common/test/test_shelf_item_delegate.cc
diff --git a/ash/common/test/test_shelf_item_delegate.cc b/ash/common/test/test_shelf_item_delegate.cc
index e086259bdaff750ced8f7ee719d9e8098cb831a9..e257d6e2aad55e25adb5dd9cdf77c3b0e958da77 100644
--- a/ash/common/test/test_shelf_item_delegate.cc
+++ b/ash/common/test/test_shelf_item_delegate.cc
@@ -26,9 +26,9 @@ ShelfItemDelegate::PerformedAction TestShelfItemDelegate::ItemSelected(
   return kNoAction;
 }
 
-ui::SimpleMenuModel* TestShelfItemDelegate::CreateApplicationMenu(
-    int event_flags) {
-  return nullptr;
+ShelfAppMenuItemList TestShelfItemDelegate::GetAppMenuItems(int event_flags) {
+  // Return an empty item list to avoid showing an application menu.
+  return ShelfAppMenuItemList();
 }
 
 void TestShelfItemDelegate::Close() {}