net: Cleanup class/struct forward declarations

net/url_request/http_user_agent_settings.h

 // Copyright (c) 2012 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_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_
 #define NET_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "net/base/net_export.h"
 
-class GURL;
-
 namespace net {
 
 // The interface used by HTTP jobs to retrieve HTTP Accept-Language
 // and User-Agent header values.
 class NET_EXPORT HttpUserAgentSettings {
  public:
   HttpUserAgentSettings() {}
   virtual ~HttpUserAgentSettings() {}
 
   // Gets the value of 'Accept-Language' header field.
   virtual std::string GetAcceptLanguage() const = 0;
 
   // Gets the UA string.
   virtual std::string GetUserAgent() const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HttpUserAgentSettings);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_HTTP_USER_AGENT_SETTINGS_H_