Simplify the user agent code some more since after r255534 it's not affected by the site's URL.

net/url_request/static_http_user_agent_settings.cc

 // 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.
 
 #include "net/url_request/static_http_user_agent_settings.h"
 
 namespace net {
 
 StaticHttpUserAgentSettings::StaticHttpUserAgentSettings(
     const std::string& accept_language,
     const std::string& user_agent)
     : accept_language_(accept_language),
       user_agent_(user_agent) {
 }
 
 StaticHttpUserAgentSettings::~StaticHttpUserAgentSettings() {
 }
 
 std::string StaticHttpUserAgentSettings::GetAcceptLanguage() const {
   return accept_language_;
 }
 
-std::string StaticHttpUserAgentSettings::GetUserAgent(const GURL& url) const {
+std::string StaticHttpUserAgentSettings::GetUserAgent() const {
   return user_agent_;
 }
 
 }  // namespace net