Add Shelf context menus for ARC in AppService.

BUG=1038487

Change-Id: I0bfd6721faee80fe02c85da07ad329085c68afaa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2011466Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733516}

chrome/browser/apps/app_service/arc_apps.cc

@@ -525,6 +525,11 @@ void ArcApps::GetMenuModel(const std::string& app_id,
                    &menu_items);
   }
 
+  if (menu_type == apps::mojom::MenuType::kShelf &&
+      base::Contains(app_id_to_task_ids_, app_id)) {
+    AddCommandItem(ash::MENU_CLOSE, IDS_SHELF_CONTEXT_MENU_CLOSE, &menu_items);
+  }
+
   std::move(callback).Run(std::move(menu_items));
 }