Add --use-more-webui runtime flag to toggle WebUI replacements for native dialogs.

chrome/browser/ui/webui/chrome_web_ui.cc

 // Copyright (c) 2011 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/webui/chrome_web_ui.h"
 
+#include "base/command_line.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/common/chrome_switches.h"
 #include "content/browser/tab_contents/tab_contents.h"
 
+#if defined(TOOLKIT_VIEWS)
+#include "views/widget/widget.h"
+#endif
+
 ChromeWebUI::ChromeWebUI(TabContents* contents)
     : WebUI(contents),
       force_bookmark_bar_visible_(false) {
 }
 
 ChromeWebUI::~ChromeWebUI() {
 }
 
 Profile* ChromeWebUI::GetProfile() const {
   return Profile::FromBrowserContext(tab_contents()->browser_context());
 }
+
+// static
+bool ChromeWebUI::IsMoreWebUI() {
+  bool more_webui = CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kUseMoreWebUI);
+#if defined(TOOLKIT_VIEWS)
+  more_webui |= views::Widget::IsPureViews();
+#endif
+  return more_webui;
+}