[Merge To M54]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 c28deda79fad5bbbabba6088962b1885fe952160..f0c43370e043cbd680b1e402a0c784dd872a65ee 100644
--- a/chrome/browser/sync/test/integration/sync_arc_package_helper.cc
+++ b/chrome/browser/sync/test/integration/sync_arc_package_helper.cc
@@ -171,6 +171,11 @@ 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(