Prefer ScopedNestableTaskAllower over manual save/restore

chrome/browser/printing/print_view_manager.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/printing/print_view_manager.h"
 
 #include <map>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ skipping 538 matching lines @@
   // memory-bound.
   static const int kPrinterSettingsTimeout = 60000;
   base::OneShotTimer<MessageLoop> quit_timer;
   quit_timer.Start(FROM_HERE,
                    TimeDelta::FromMilliseconds(kPrinterSettingsTimeout),
                    MessageLoop::current(), &MessageLoop::Quit);
 
   inside_inner_message_loop_ = true;
 
   // Need to enable recursive task.
-  bool old_state = MessageLoop::current()->NestableTasksAllowed();
-  MessageLoop::current()->SetNestableTasksAllowed(true);
-  MessageLoop::current()->Run();
-  // Restore task state.
-  MessageLoop::current()->SetNestableTasksAllowed(old_state);
+  {
+    MessageLoop::ScopedNestableTaskAllower allow(MessageLoop::current());
+    MessageLoop::current()->Run();
+  }
 
   bool success = true;
   if (inside_inner_message_loop_) {
     // Ok we timed out. That's sad.
     inside_inner_message_loop_ = false;
     success = false;
   }
 
   return success;
 }
@@ skipping 29 matching lines @@
 }
 
 bool PrintViewManager::PrintNowInternal(IPC::Message* message) {
   // Don't print / print preview interstitials.
   if (web_contents()->ShowingInterstitialPage())
     return false;
   return Send(message);
 }
 
 }  // namespace printing