Make the proxy server HostPortPair available in document_state so that

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index e383c3fb31e6786bfcf02c00b74513d7d8eab17d..66ba187c5f8d42ac86fab7430125a912c532b370 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -2921,6 +2921,8 @@ void RenderFrameImpl::didReceiveResponse(
         extra_data->connection_info());
     document_state->set_was_fetched_via_proxy(
         extra_data->was_fetched_via_proxy());
+    document_state->set_proxy_server(
+        extra_data->proxy_server());
   }
   InternalDocumentStateData* internal_data =
       InternalDocumentStateData::FromDocumentState(document_state);