Prefer ScopedNestableTaskAllower over manual save/restore

chrome/browser/ui/views/tab_contents/tab_contents_view_views.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/ui/views/tab_contents/tab_contents_view_views.h"
 
 #include <vector>
 
 #include "base/time.h"
 #include "chrome/browser/ui/constrained_window.h"
@@ skipping 343 matching lines @@
 
   // Don't show empty menus.
   if (context_menu_->menu_model().GetItemCount() == 0)
     return;
 
   gfx::Point screen_point(params.x, params.y);
   views::View::ConvertPointToScreen(GetRootView(), &screen_point);
 
   // Enable recursive tasks on the message loop so we can get updates while
   // the context menu is being displayed.
-  bool old_state = MessageLoop::current()->NestableTasksAllowed();
-  MessageLoop::current()->SetNestableTasksAllowed(true);
+  MessageLoop::ScopedNestableTaskAllower allow(MessageLoop::current());
   context_menu_->RunMenuAt(screen_point.x(), screen_point.y());
-  MessageLoop::current()->SetNestableTasksAllowed(old_state);
 }
 
 void TabContentsViewViews::ShowPopupMenu(const gfx::Rect& bounds,
                                          int item_height,
                                          double item_font_size,
                                          int selected_item,
                                          const std::vector<WebMenuItem>& items,
                                          bool right_aligned) {
   // External popup menus are only used on Mac.
   NOTREACHED();
@@ skipping 91 matching lines @@
     web_contents_->HideContents();
   }
 }
 
 void TabContentsViewViews::OnNativeWidgetSizeChanged(
     const gfx::Size& new_size) {
   if (overlaid_view_)
     overlaid_view_->SetBounds(gfx::Rect(new_size));
   views::Widget::OnNativeWidgetSizeChanged(new_size);
 }