Add request_id to HttpRequestInfo and pass it to the NetworkDelegate for events.

net/http/http_request_info.h

 // Copyright (c) 2006-2008 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 NET_HTTP_HTTP_REQUEST_INFO_H__
 #define NET_HTTP_HTTP_REQUEST_INFO_H__
 #pragma once
 
 #include <string>
 #include "base/ref_counted.h"
@@ skipping 34 matching lines @@
   scoped_refptr<UploadData> upload_data;
 
   // Any load flags (see load_flags.h).
   int load_flags;
 
   // The priority level for this request.
   RequestPriority priority;
 
   // The motivation behind this request.
   RequestMotivation motivation;
+
+  // An optional globally unique identifier for this request for use by the
+  // consumer. 0 is invalid.
+  uint64 request_id;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_REQUEST_INFO_H__