Move some content url constants to /url.

url/url_srcs.gypi

 # Copyright 2014 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.
 
 {
   'variables': {
     'gurl_sources': [
       'gurl.cc',
       'gurl.h',
       'origin.cc',
@@ skipping 12 matching lines @@
       'url_canon_internal_file.h',
       'url_canon_ip.cc',
       'url_canon_ip.h',
       'url_canon_mailtourl.cc',
       'url_canon_path.cc',
       'url_canon_pathurl.cc',
       'url_canon_query.cc',
       'url_canon_relative.cc',
       'url_canon_stdstring.cc',
       'url_canon_stdurl.cc',
+      'url_constants.cc',
+      'url_constants.h',
       'url_file.h',
       'url_parse_file.cc',
       'url_parse_internal.h',
       'url_util.cc',
       'url_util.h',
     ],
   },
 }