Move some content url constants to /url.

url/url_util_internal.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 URL_URL_UTIL_INTERNAL_H_
 #define URL_URL_UTIL_INTERNAL_H_
 
 #include <string>
 
 #include "base/strings/string16.h"
 #include "url/url_parse.h"
 
 namespace url {
 
-extern const char kFileScheme[];
-extern const char kFileSystemScheme[];
-extern const char kMailtoScheme[];
-
 // Given a string and a range inside the string, compares it to the given
 // lower-case |compare_to| buffer.
 bool CompareSchemeComponent(const char* spec,
                             const Component& component,
                             const char* compare_to);
 bool CompareSchemeComponent(const base::char16* spec,
                             const Component& component,
                             const char* compare_to);
 
 }  // namespace url
 
 #endif  // URL_URL_UTIL_INTERNAL_H_