mash: Use ChromeLauncherControllerImpl, remove Mus subclass stub.

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

Index: chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.cc
diff --git a/chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.cc b/chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.cc
index 14af509dfc363e161714cdf888f8cdf04ad7d694..ec8abca5a2bfbb3cd9a8996505cee96bc9efc0a1 100644
--- a/chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.cc
+++ b/chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.cc
@@ -5,7 +5,6 @@
 #include "chrome/browser/ui/ash/launcher/arc_app_deferred_launcher_controller.h"
 
 #include "ash/shelf/shelf_model.h"
-#include "ash/shell.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/chromeos/arc/arc_util.h"
@@ -113,9 +112,8 @@ void ArcAppDeferredLauncherController::Close(const std::string& app_id) {
     return;
 
   const ash::ShelfID shelf_id = owner_->GetShelfIDForAppID(shelf_app_id);
-  ash::ShelfModel* shelf_model = ash::Shell::Get()->shelf_model();
   const bool need_close_item =
-      it->second == shelf_model->GetShelfItemDelegate(shelf_id);
+      it->second == owner_->shelf_model()->GetShelfItemDelegate(shelf_id);
   app_controller_map_.erase(it);
   if (need_close_item)
     owner_->CloseLauncherItem(shelf_id);
@@ -213,8 +211,8 @@ void ArcAppDeferredLauncherController::RegisterDeferredLaunch(
   if (shelf_id == 0) {
     owner_->CreateAppLauncherItem(std::move(controller), ash::STATUS_RUNNING);
   } else {
-    ash::ShelfModel* shelf_model = ash::Shell::Get()->shelf_model();
-    shelf_model->SetShelfItemDelegate(shelf_id, std::move(controller));
+    owner_->shelf_model()->SetShelfItemDelegate(shelf_id,
+                                                std::move(controller));
     owner_->SetItemStatus(shelf_id, ash::STATUS_RUNNING);
   }