[Merge to M53]arc: Enable user control for Arc package sync.

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

Index: chrome/browser/ui/app_list/arc/arc_app_list_prefs.cc
diff --git a/chrome/browser/ui/app_list/arc/arc_app_list_prefs.cc b/chrome/browser/ui/app_list/arc/arc_app_list_prefs.cc
index bcdb6d21d9a43e57ad33daf5e088d2557846ff4d..de19ba3fdb48d69b29405584dea515ada5df0ecd 100644
--- a/chrome/browser/ui/app_list/arc/arc_app_list_prefs.cc
+++ b/chrome/browser/ui/app_list/arc/arc_app_list_prefs.cc
@@ -585,9 +585,6 @@ void ArcAppListPrefs::OnInstanceReady() {
 
   app_instance->Init(binding_.CreateInterfacePtrAndBind());
   app_instance->RefreshAppList();
-
-  // Start ArcPackageSyncService.
-  sync_service_->SyncStarted();
 }
 
 void ArcAppListPrefs::OnInstanceClosed() {
@@ -989,6 +986,13 @@ void ArcAppListPrefs::OnPackageListRefreshed(
     if (!current_packages.count(package_name))
       RemovePackageFromPrefs(prefs_, package_name);
   }
+
+  // Start ArcPackageSyncService ASAP. This is the call_back of
+  // app_instance->RefreshAppList() in OnInstanceReady(). SyncStarted() should
+  // only be called after packagelist refresh is completed. SyncStarted() is
+  // no-op after first time setup or if sync is disabled.
+  DCHECK(sync_service_);
+  sync_service_->SyncStarted();
 }
 
 std::vector<std::string> ArcAppListPrefs::GetPackagesFromPrefs() const {