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

chrome/test/pyautolib/pyautolib.cc

Index: chrome/test/pyautolib/pyautolib.cc
diff --git a/chrome/test/pyautolib/pyautolib.cc b/chrome/test/pyautolib/pyautolib.cc
index 3db59eb2682ff41d710a798d67b91eb94770dbc7..0769d6d9158200697b63c7377c8ebd3d7dd9e95f 100644
--- a/chrome/test/pyautolib/pyautolib.cc
+++ b/chrome/test/pyautolib/pyautolib.cc
@@ -69,7 +69,12 @@ void PyUITestBase::Initialize(const FilePath& browser_dir) {
 ProxyLauncher* PyUITestBase::CreateProxyLauncher() {
   if (named_channel_id_.empty())
     return new AnonymousProxyLauncher(false);
-  return new NamedProxyLauncher(named_channel_id_, false, false);
+
+  NamedProxyLauncher::InitParams params;
+  params.launch_browser = false;
+  params.disconnect_on_failure = false;
+  params.wait_for_server_channel = true;
+  return new NamedProxyLauncher(named_channel_id_, params);
 }
 
 void PyUITestBase::SetUp() {