Prefer ScopedNestableTaskAllower over manual save/restore

chrome/test/base/ui_test_utils.cc

Index: chrome/test/base/ui_test_utils.cc
diff --git a/chrome/test/base/ui_test_utils.cc b/chrome/test/base/ui_test_utils.cc
index dc6876460af634751ca0e9fd55d8414fefa877c4..6a580d79e8a6d497ebc92ebcd8689cd2214ee501 100644
--- a/chrome/test/base/ui_test_utils.cc
+++ b/chrome/test/base/ui_test_utils.cc
@@ -266,8 +266,7 @@ void RunMessageLoop() {
   MessageLoopForUI* ui_loop =
       content::BrowserThread::CurrentlyOn(content::BrowserThread::UI) ?
           MessageLoopForUI::current() : NULL;
-  bool did_allow_task_nesting = loop->NestableTasksAllowed();
-  loop->SetNestableTasksAllowed(true);
+  MessageLoop::ScopedNestableTaskAllower allow(loop);
   if (ui_loop) {
 #if defined(USE_AURA)
     aura::RootWindow::GetInstance()->Run();
@@ -282,7 +281,6 @@ void RunMessageLoop() {
   } else {
     loop->Run();
   }
-  loop->SetNestableTasksAllowed(did_allow_task_nesting);
 }
 
 void RunAllPendingInMessageLoop() {