Sync: Support multiple setup UIs.

chrome/browser/supervised_user/supervised_user_service.h

Index: chrome/browser/supervised_user/supervised_user_service.h
diff --git a/chrome/browser/supervised_user/supervised_user_service.h b/chrome/browser/supervised_user/supervised_user_service.h
index 8e93e7576efa31e5e2a529401eb1d559d8a2536a..92269767eb8768065c2bec107bbd566f2335ffa9 100644
--- a/chrome/browser/supervised_user/supervised_user_service.h
+++ b/chrome/browser/supervised_user/supervised_user_service.h
@@ -60,6 +60,10 @@ namespace extensions {
 class ExtensionRegistry;
 }
 
+namespace sync_driver {
+class SyncSetupInProgressHandle;
+}
+
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
@@ -409,6 +413,9 @@ class SupervisedUserService : public KeyedService,
 
   base::ObserverList<SupervisedUserServiceObserver> observer_list_;
 
+  // Prevents Sync from running until configuration is complete.
+  std::unique_ptr<sync_driver::SyncSetupInProgressHandle> sync_blocker_;
+
   base::WeakPtrFactory<SupervisedUserService> weak_ptr_factory_;
 };