revert r71405 as it is causing ui test failures:

chrome/renderer/render_thread.cc

 // Copyright (c) 2010 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/renderer/render_thread.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 846 matching lines @@
   WebKit::initialize(webkit_client_.get());
 
   WebScriptController::enableV8SingleThreadMode();
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   // chrome: pages should not be accessible by normal content, and should
   // also be unable to script anything but themselves (to help limit the damage
   // that a corrupt chrome: page could cause).
   WebString chrome_ui_scheme(ASCIIToUTF16(chrome::kChromeUIScheme));
-  WebSecurityPolicy::registerURLSchemeAsDisplayIsolated(chrome_ui_scheme);
+  if (command_line.HasSwitch(switches::kNewChromeUISecurityModel)) {
+    WebSecurityPolicy::registerURLSchemeAsDisplayIsolated(chrome_ui_scheme);
+  } else {
+    WebSecurityPolicy::registerURLSchemeAsLocal(chrome_ui_scheme);
+    WebSecurityPolicy::registerURLSchemeAsNoAccess(chrome_ui_scheme);
+  }
 
   // chrome-extension: resources shouldn't trigger insecure content warnings.
   WebString extension_scheme(ASCIIToUTF16(chrome::kExtensionScheme));
   WebSecurityPolicy::registerURLSchemeAsSecure(extension_scheme);
 
 #if defined(OS_WIN)
   // We don't yet support Gears on non-Windows, so don't tell pages that we do.
   RegisterExtension(extensions_v8::GearsExtension::Get(), false);
 #endif
   RegisterExtension(extensions_v8::LoadTimesExtension::Get(), false);
@@ skipping 254 matching lines @@
   }
 
   return false;
 }
 
 void RenderThread::RegisterExtension(v8::Extension* extension,
                                      bool restrict_to_extensions) {
   WebScriptController::registerExtension(extension);
   v8_extensions_[extension->name()] = restrict_to_extensions;
 }