arc: Fix race when arc package sync service starts.

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 b86400a65d6f48420e2ca720407d9504d8bd7cda..708dd83372fb2bbe16e4c48e13de0ddc45dbb1ab 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
@@ -666,6 +666,7 @@ void ArcAppListPrefs::OnInstanceClosed() {
   }
 
   is_initialized_ = false;
+  package_list_initial_refreshed_ = false;
 }
 
 void ArcAppListPrefs::MaybeAddNonLaunchableApp(const std::string& name,
@@ -1132,12 +1133,13 @@ void ArcAppListPrefs::OnPackageListRefreshed(
       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();
+  // TODO(lgcheng@) File http://b/31944261. Remove the flag after Android side
+  // cleanup.
+  if (package_list_initial_refreshed_)
+    return;
+
+  package_list_initial_refreshed_ = true;
+  FOR_EACH_OBSERVER(Observer, observer_list_, OnPackageListInitialRefreshed());
 }
 
 std::vector<std::string> ArcAppListPrefs::GetPackagesFromPrefs() const {