Make the proxy server HostPortPair available in document_state so that

content/public/renderer/document_state.h

Index: content/public/renderer/document_state.h
diff --git a/content/public/renderer/document_state.h b/content/public/renderer/document_state.h
index 11b7d5e10bfdee31939614cafb452b8ecfe3f078..d388a8a979ef0dcdc695ac86221ce470409ffce7 100644
--- a/content/public/renderer/document_state.h
+++ b/content/public/renderer/document_state.h
@@ -161,6 +161,11 @@ class CONTENT_EXPORT DocumentState
     was_fetched_via_proxy_ = value;
   }
 
+  net::HostPortPair proxy_server() const { return proxy_server_; }
+  void set_proxy_server(net::HostPortPair proxy_server) {
+    proxy_server_ = proxy_server;
+  }
+
   void set_was_prefetcher(bool value) { was_prefetcher_ = value; }
   bool was_prefetcher() const { return was_prefetcher_; }
 
@@ -204,6 +209,7 @@ class CONTENT_EXPORT DocumentState
   bool was_alternate_protocol_available_;
   net::HttpResponseInfo::ConnectionInfo connection_info_;
   bool was_fetched_via_proxy_;
+  net::HostPortPair proxy_server_;
 
   // A prefetcher is a page that contains link rel=prefetch elements.
   bool was_prefetcher_;