arc: Fix race when arc package sync service starts.

chrome/browser/sync/test/integration/sync_arc_package_helper.cc

Index: chrome/browser/sync/test/integration/sync_arc_package_helper.cc
diff --git a/chrome/browser/sync/test/integration/sync_arc_package_helper.cc b/chrome/browser/sync/test/integration/sync_arc_package_helper.cc
index 7a146a35b38a795a6db5c0b9d2194d227bb8c8d4..609c855e72441f3a77dc9dde6577233b5ee9f7dc 100644
--- a/chrome/browser/sync/test/integration/sync_arc_package_helper.cc
+++ b/chrome/browser/sync/test/integration/sync_arc_package_helper.cc
@@ -170,6 +170,11 @@ void SyncArcPackageHelper::SetupArcService(Profile* profile, size_t id) {
   DCHECK(instance_map_[profile].get());
   arc_app_list_prefs->app_instance_holder()->SetInstance(
       instance_map_[profile].get());
+  // OnPackageListRefreshed will be called when AppInstance is ready.
+  // For fakeAppInstance we use SendRefreshPackageList to make sure that
+  // OnPackageListRefreshed will be called.
+  instance_map_[profile]->SendRefreshPackageList(
+      std::vector<arc::mojom::ArcPackageInfo>());
 }
 
 void SyncArcPackageHelper::InstallPackage(