Prefer ScopedNestableTaskAllower over manual save/restore

chrome/browser/ui/views/simple_message_box_views.cc

Index: chrome/browser/ui/views/simple_message_box_views.cc
diff --git a/chrome/browser/ui/views/simple_message_box_views.cc b/chrome/browser/ui/views/simple_message_box_views.cc
index d295c3893f18025551146c507c87fd76d28ef7e3..8bfe41d85acee15153924917a8cc0d4b9901f11e 100644
--- a/chrome/browser/ui/views/simple_message_box_views.cc
+++ b/chrome/browser/ui/views/simple_message_box_views.cc
@@ -62,10 +62,10 @@ bool SimpleMessageBoxViews::ShowYesNoBox(gfx::NativeWindow parent_window,
 #if defined(USE_AURA)
   aura::client::GetDispatcherClient()->RunWithDispatcher(dialog, true);
 #else
-  bool old_state = MessageLoopForUI::current()->NestableTasksAllowed();
-  MessageLoopForUI::current()->SetNestableTasksAllowed(true);
-  MessageLoopForUI::current()->RunWithDispatcher(dialog);
-  MessageLoopForUI::current()->SetNestableTasksAllowed(old_state);
+  {
+    MessageLoop::ScopedNestableTaskAllower allow(MessageLoopForUI::current());
+    MessageLoopForUI::current()->RunWithDispatcher(dialog);
+  }
 #endif
 
   g_browser_process->ReleaseModule();

[jar (doing other things), 2012/02/11 03:24:38]

nit/curious question: What are the potential side effects of this
ReleaseModule()?  How much destruction can take place, or is it all just posted
events, and that is why it is safe to do now (and not while we're in a
sub-loop)?

[dhollowa, 2012/02/13 17:44:26]

This is meant to match the |AddRefModule| at line 60, a guard against shutdown
with the dialog up.  If this is the last "release" then quit messages are posted
to the IO thread and the main UI thread is "Quit".  This seems ok.