Use AuthCredentials throughout the network stack instead of username/password.

net/http/http_stream_factory_impl_request.cc

Index: net/http/http_stream_factory_impl_request.cc
diff --git a/net/http/http_stream_factory_impl_request.cc b/net/http/http_stream_factory_impl_request.cc
index 17c717e00b29967f69854253930b345ad1ef5ebd..493aa431d99d987a7d99b0fb9178d8436785546e 100644
--- a/net/http/http_stream_factory_impl_request.cc
+++ b/net/http/http_stream_factory_impl_request.cc
@@ -196,10 +196,9 @@ void HttpStreamFactoryImpl::Request::OnHttpsProxyTunnelResponse(
 }
 
 int HttpStreamFactoryImpl::Request::RestartTunnelWithProxyAuth(
-    const string16& username,
-    const string16& password) {
+    const AuthCredentials& credentials) {
   DCHECK(bound_job_.get());
-  return bound_job_->RestartTunnelWithProxyAuth(username, password);
+  return bound_job_->RestartTunnelWithProxyAuth(credentials);
 }
 
 LoadState HttpStreamFactoryImpl::Request::GetLoadState() const {