Let pyauto create an attached webdriver instance to manipulate web pages.

chrome/test/pyautolib/pyautolib.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 "base/memory/scoped_ptr.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/test/automation/automation_proxy.h"
 #include "chrome/test/automation/extension_proxy.h"
@@ skipping 51 matching lines @@
   return message_loop_;
 }
 
 void PyUITestBase::Initialize(const FilePath& browser_dir) {
   UITestBase::SetBrowserDirectory(browser_dir);
 }
 
 ProxyLauncher* PyUITestBase::CreateProxyLauncher() {
   if (named_channel_id_.empty())
     return new AnonymousProxyLauncher(false);
-  return new NamedProxyLauncher(named_channel_id_, false, false);
+  return new NamedProxyLauncher(named_channel_id_, false, true, false);
 }
 
 void PyUITestBase::SetUp() {
   UITestBase::SetUp();
 }
 
 void PyUITestBase::TearDown() {
   UITestBase::TearDown();
 }
 
@@ skipping 315 matching lines @@
   // TODO(phadjan.jr): figure out a way to unambiguously report error.
   if (!browser_proxy.get())
     return cookie_val;
   scoped_refptr<TabProxy> tab_proxy = browser_proxy->GetTab(tab_index);
   EXPECT_TRUE(tab_proxy.get());
   if (!tab_proxy.get())
     return cookie_val;
   EXPECT_TRUE(tab_proxy->GetCookies(cookie_url, &cookie_val));
   return cookie_val;
 }