Use of base::StringPairs appropriately in server

net/server/http_server_response_info.h

 // Copyright 2013 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_SERVER_HTTP_SERVER_RESPONSE_INFO_H_
 #define NET_SERVER_HTTP_SERVER_RESPONSE_INFO_H_
 
 #include <string>
 #include <utility>
-#include <vector>
 
+#include "base/strings/string_split.h"
 #include "net/http/http_status_code.h"
 
 namespace net {
 
 class HttpServerResponseInfo {
  public:
   // Creates a 200 OK HttpServerResponseInfo.
   HttpServerResponseInfo();
   explicit HttpServerResponseInfo(HttpStatusCode status_code);
   ~HttpServerResponseInfo();
 
   static HttpServerResponseInfo CreateFor404();
   static HttpServerResponseInfo CreateFor500(const std::string& body);
 
   void AddHeader(const std::string& name, const std::string& value);
 
   // This also adds an appropriate Content-Length header.
   void SetBody(const std::string& body, const std::string& content_type);
   // Sets content-length and content-type. Body should be sent separately.
   void SetContentHeaders(size_t content_length,
                          const std::string& content_type);
 
   std::string Serialize() const;
 
   HttpStatusCode status_code() const;
   const std::string& body() const;
 
  private:
-  typedef std::vector<std::pair<std::string, std::string> > Headers;
+  using Headers = base::StringPairs;
 
   HttpStatusCode status_code_;
   Headers headers_;
   std::string body_;
 };
 
 }  // namespace net
 
 #endif  // NET_SERVER_HTTP_SERVER_RESPONSE_INFO_H_