mash: Replace int ShelfIDs with AppLaunchID strings.

chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_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_deferred_launcher_controller.h"
 
 #include "ash/shelf/shelf_model.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/chromeos/arc/arc_util.h"
@@ skipping 190 matching lines @@
 
   // We are allowed to apply new deferred controller only over non-active items.
   const ash::ShelfItem* item = owner_->GetItem(shelf_id);
   if (item && item->status != ash::STATUS_CLOSED)
     return;
 
   std::unique_ptr<ArcAppDeferredLauncherItemController> controller =
       base::MakeUnique<ArcAppDeferredLauncherItemController>(
           shelf_app_id, event_flags, weak_ptr_factory_.GetWeakPtr());
   ArcAppDeferredLauncherItemController* item_controller = controller.get();
-  if (shelf_id == 0) {
+  if (shelf_id.IsNull()) {
     owner_->CreateAppLauncherItem(std::move(controller), ash::STATUS_RUNNING);
   } else {
     owner_->shelf_model()->SetShelfItemDelegate(shelf_id,
                                                 std::move(controller));
     owner_->SetItemStatus(shelf_id, ash::STATUS_RUNNING);
   }
 
   if (app_controller_map_.empty())
     RegisterNextUpdate();
 
   app_controller_map_[shelf_app_id] = item_controller;
 }