arc: Fix regression in handling ARC shelf item.

chrome/browser/ui/ash/launcher/arc_app_window_launcher_item_controller.cc

 // Copyright 2016 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 "chrome/browser/ui/ash/launcher/arc_app_window_launcher_item_controller.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/app_list/arc/arc_app_list_prefs.h"
@@ skipping 36 matching lines @@
 
   if (task_ids_.empty()) {
     NOTREACHED();
     callback.Run(ash::SHELF_ACTION_NONE, base::nullopt);
     return;
   }
   arc::SetTaskActive(*task_ids_.begin());
   callback.Run(ash::SHELF_ACTION_NEW_WINDOW_CREATED, base::nullopt);
 }
 
+void ArcAppWindowLauncherItemController::ExecuteCommand(uint32_t command_id,
+                                                        int32_t event_flags) {
+  ActivateIndexedApp(command_id);
+}
+
 MenuItemList ArcAppWindowLauncherItemController::GetAppMenuItems(
     int event_flags) {
   MenuItemList items;
   base::string16 app_title = LauncherControllerHelper::GetAppTitle(
       launcher_controller()->profile(), app_id());
   for (auto it = windows().begin(); it != windows().end(); ++it) {
     // TODO(khmel): resolve correct icon here.
     size_t i = std::distance(windows().begin(), it);
     aura::Window* window = (*it)->GetNativeWindow();
     ash::mojom::MenuItemPtr item = ash::mojom::MenuItem::New();
     item->command_id = base::checked_cast<uint32_t>(i);
     item->label = (window && !window->GetTitle().empty()) ? window->GetTitle()
                                                           : app_title;
     items.push_back(std::move(item));
   }
   return items;
 }