Fix Arc integration test.

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

Index: chrome/browser/sync/test/integration/single_client_arc_package_sync_test.cc
diff --git a/chrome/browser/sync/test/integration/single_client_arc_package_sync_test.cc b/chrome/browser/sync/test/integration/single_client_arc_package_sync_test.cc
index 7f948b2d5c8292ec9b60ed8dbeb7cf0fc7017db5..280ff89b106ceb1365ed71b9c048d75c522c9442 100644
--- a/chrome/browser/sync/test/integration/single_client_arc_package_sync_test.cc
+++ b/chrome/browser/sync/test/integration/single_client_arc_package_sync_test.cc
@@ -6,6 +6,7 @@
 #include "chrome/browser/sync/test/integration/sync_arc_package_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
+#include "chrome/browser/ui/app_list/arc/arc_app_list_prefs_factory.h"
 #include "chrome/browser/ui/app_list/arc/arc_package_syncable_service.h"
 
 namespace arc {
@@ -36,6 +37,10 @@ class SingleClientArcPackageSyncTest : public SyncTest {
     return sync_helper_ != nullptr;
   }
 
+  void SetUpOnMainThread() override {

[lgcheng, 2017/02/22 23:36:44]

Moved from sync_arc_package_helper. It seems the execution order of
SetFactoryForSyncTest() and setupService() is not guaranteed by compiler due to
the complexity of construction of ArcAppListPrefs. 

+    ArcAppListPrefsFactory::SetFactoryForSyncTest();
+  }
+
   void TearDownOnMainThread() override {
     sync_helper_->CleanUp();
     sync_helper_ = nullptr;