Use HttpRequestHeaders for extra_headers.

net/http/http_vary_data.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_VARY_DATA_H__
 #define NET_HTTP_HTTP_VARY_DATA_H__
 
 #include "base/md5.h"
 
 class Pickle;
 
 namespace net {
 
-class HttpRequestInfo;
+struct HttpRequestInfo;
 class HttpResponseHeaders;
 
 // Used to implement the HTTP/1.1 Vary header.  This class contains a MD5 hash
 // over the request headers indicated by a Vary header.
 //
 // While RFC 2616 requires strict request header comparisons, it is much
 // cheaper to store a MD5 sum, which should be sufficient.  Storing a hash also
 // avoids messy privacy issues as some of the request headers could hold
 // sensitive data (e.g., cookies).
 //
@@ skipping 50 matching lines @@
   // A digested version of the request headers corresponding to the Vary header.
   MD5Digest request_digest_;
 
   // True when request_digest_ contains meaningful data.
   bool is_valid_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_VARY_DATA_H__