Prefer ScopedNestableTaskAllower over manual save/restore

chrome/browser/sessions/session_restore.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/sessions/session_restore.h"
 
 #if defined(OS_WIN)
 #include <malloc.h>
 #else
 #include <alloca.h>
@@ skipping 457 matching lines @@
 
   Browser* Restore() {
     SessionService* session_service =
         SessionServiceFactory::GetForProfile(profile_);
     DCHECK(session_service);
     session_service->GetLastSession(
         &request_consumer_,
         base::Bind(&SessionRestoreImpl::OnGotSession, base::Unretained(this)));
 
     if (synchronous_) {
-      bool old_state = MessageLoop::current()->NestableTasksAllowed();
-      MessageLoop::current()->SetNestableTasksAllowed(true);
-      MessageLoop::current()->Run();
-      MessageLoop::current()->SetNestableTasksAllowed(old_state);
+      {
+        MessageLoop::ScopedNestableTaskAllower allow(MessageLoop::current());
+        MessageLoop::current()->Run();
+      }
       Browser* browser = ProcessSessionWindows(&windows_);
       delete this;
       return browser;
     }
 
     if (browser_) {
       registrar_.Add(this, chrome::NOTIFICATION_BROWSER_CLOSED,
                      content::Source<Browser>(browser_));
     }
 
@@ skipping 484 matching lines @@
   if (active_session_restorers == NULL)
     return false;
   for (std::set<SessionRestoreImpl*>::const_iterator it =
            active_session_restorers->begin();
        it != active_session_restorers->end(); ++it) {
     if ((*it)->profile() == profile)
       return true;
   }
   return false;
 }