Move user_agent code from webkit/ to content/.

webkit/common/user_agent/user_agent.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 WEBKIT_COMMON_USER_AGENT_USER_AGENT_H_
-#define WEBKIT_COMMON_USER_AGENT_USER_AGENT_H_
-
-#include <string>
-
-#include "base/basictypes.h"
-#include "url/gurl.h"
-#include "webkit/common/user_agent/webkit_user_agent_export.h"
-
-namespace webkit_glue {
-
-// Sets the user agent.  Pass true for overriding if this is a custom
-// user agent instead of the default one (in order to turn off any browser
-// sniffing workarounds). This must be called before GetUserAgent() can
-// be called.
-WEBKIT_USER_AGENT_EXPORT void SetUserAgent(const std::string& user_agent,
-                                           bool overriding);
-
-// Returns the user agent to use for the given URL. SetUserAgent() must
-// be called prior to calling this function.
-WEBKIT_USER_AGENT_EXPORT const std::string& GetUserAgent(const GURL& url);
-
-}  // namespace webkit_glue
-
-#endif  // WEBKIT_COMMON_USER_AGENT_USER_AGENT_H_