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

chrome/browser/ui/webui/html_dialog_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/html_dialog_ui.h"
 
 #include "base/callback.h"
 #include "base/lazy_instance.h"
 #include "base/values.h"
 #include "content/browser/renderer_host/render_view_host.h"
@@ skipping 11 matching lines @@
   // Don't unregister our property. During the teardown of the TabContents,
   // this will be deleted, but the TabContents will already be destroyed.
   //
   // This object is owned indirectly by the TabContents. WebUIs can change, so
   // it's scary if this WebUI is changed out and replaced with something else,
   // since the property will still point to the old delegate. But the delegate
   // is itself the owner of the TabContents for a dialog so will be in scope,
   // and the HTML dialogs won't swap WebUIs anyway since they don't navigate.
 }
 
+void HtmlDialogUI::CloseDialog(const base::ListValue* args) {
+  OnDialogClosed(args);
+}
+
 // static
 PropertyAccessor<HtmlDialogUIDelegate*>& HtmlDialogUI::GetPropertyAccessor() {
   return g_html_dialog_ui_property_accessor.Get();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Private:
 
 void HtmlDialogUI::RenderViewCreated(RenderViewHost* render_view_host) {
   // Hook up the javascript function calls, also known as chrome.send("foo")
@@ skipping 18 matching lines @@
     (*it)->Attach(this);
     AddMessageHandler(*it);
   }
 }
 
 void HtmlDialogUI::OnDialogClosed(const ListValue* args) {
   HtmlDialogUIDelegate** delegate = GetPropertyAccessor().GetProperty(
       tab_contents()->property_bag());
   if (delegate) {
     std::string json_retval;
-    if (!args->GetString(0, &json_retval))
-      NOTREACHED() << "Could not read JSON arguments";
+    if (args && !args->empty() && !args->GetString(0, &json_retval))
+      NOTREACHED() << "Could not read JSON argument";
 
     (*delegate)->OnDialogClosed(json_retval);
   }
 }
 
 ExternalHtmlDialogUI::ExternalHtmlDialogUI(TabContents* tab_contents)
     : HtmlDialogUI(tab_contents) {
   // Non-file based UI needs to not have access to the Web UI bindings
   // for security reasons. The code hosting the dialog should provide
   // dialog specific functionality through other bindings and methods
   // that are scoped in duration to the dialogs existence.
   bindings_ &= ~BindingsPolicy::WEB_UI;
 }
 
 ExternalHtmlDialogUI::~ExternalHtmlDialogUI() {
 }
 
 bool HtmlDialogUIDelegate::HandleContextMenu(const ContextMenuParams& params) {
   return false;
 }