Reland of arc: Use the new InstanceHolder for unittests

chrome/browser/ui/app_list/arc/arc_app_test.cc

Index: chrome/browser/ui/app_list/arc/arc_app_test.cc
diff --git a/chrome/browser/ui/app_list/arc/arc_app_test.cc b/chrome/browser/ui/app_list/arc/arc_app_test.cc
index 2f0be2f8e1712f85be5fe75b35f4f0edec6c665d..313ffd93c522986fd1d242c8435e1254ac991684 100644
--- a/chrome/browser/ui/app_list/arc/arc_app_test.cc
+++ b/chrome/browser/ui/app_list/arc/arc_app_test.cc
@@ -117,10 +117,7 @@ void ArcAppTest::SetUp(Profile* profile) {
   DCHECK(arc_app_list_pref_);
 
   app_instance_.reset(new arc::FakeAppInstance(arc_app_list_pref_));
-  arc::mojom::AppInstancePtr instance;
-  app_instance_->Bind(mojo::GetProxy(&instance));
-  bridge_service_->OnAppInstanceReady(std::move(instance));
-  app_instance_->WaitForOnAppInstanceReady();
+  bridge_service_->app()->SetInstance(app_instance_.get());
 
   // Check initial conditions.
   EXPECT_EQ(bridge_service_.get(), arc::ArcBridgeService::Get());