Make the proxy server HostPortPair available in document_state so that

content/public/common/resource_response_info.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_PUBLIC_COMMON_RESOURCE_RESPONSE_INFO_H_
 #define CONTENT_PUBLIC_COMMON_RESOURCE_RESPONSE_INFO_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 75 matching lines @@
 
   // True if response could use alternate protocol. However, browser will
   // ignore the alternate protocol when spdy is not enabled on browser side.
   bool was_alternate_protocol_available;
 
   // Information about the type of connection used to fetch this response.
   net::HttpResponseInfo::ConnectionInfo connection_info;
 
   // True if the response was fetched via an explicit proxy (as opposed to a
   // transparent proxy). The proxy could be any type of proxy, HTTP or SOCKS.
-  // Note: we cannot tell if a transparent proxy may have been involved.
+  // Note: we cannot tell if a transparent proxy may have been involved. If
+  // true, |proxy_server| contains the name of the proxy server that was used.
   bool was_fetched_via_proxy;
+  net::HostPortPair proxy_server;
 
   // NPN protocol negotiated with the server.
   std::string npn_negotiated_protocol;
 
   // Remote address of the socket which fetched this resource.
   net::HostPortPair socket_address;
 
   // True if the response was fetched by a ServiceWorker.
   bool was_fetched_via_service_worker;
 
@@ skipping 13 matching lines @@
   // ServiceWorker Timing Information. These will be set if the response is
   // provided by the ServiceWorker, or kept empty.
   base::TimeTicks service_worker_fetch_start;
   base::TimeTicks service_worker_fetch_ready;
   base::TimeTicks service_worker_fetch_end;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_RESOURCE_RESPONSE_INFO_H_