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

chrome/browser/ui/cocoa/hung_renderer_controller.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/hung_renderer_controller.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/mac_util.h"
 #include "base/process_util.h"
@@ skipping 163 matching lines @@
   return killButton_;
 }
 
 - (MultiKeyEquivalentButton*)waitButton {
   return waitButton_;
 }
 @end
 
 namespace browser {
 
-void ShowHungRendererDialog(TabContents* contents) {
+void ShowNativeHungRendererDialog(TabContents* contents) {
   if (!logging::DialogsAreSuppressed()) {
     if (!g_instance)
       g_instance = [[HungRendererController alloc]
                      initWithWindowNibName:@"HungRendererDialog"];
     [g_instance showForTabContents:contents];
   }
 }
 
-void HideHungRendererDialog(TabContents* contents) {
+void HideNativeHungRendererDialog(TabContents* contents) {
   if (!logging::DialogsAreSuppressed() && g_instance)
     [g_instance endForTabContents:contents];
 }
 
 }  // namespace browser