Update checklicenses.py to allow GPL v3 in ffmpeg code

tools/checklicenses/checklicenses.py

 #!/usr/bin/env python
 # 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.
 
 """Makes sure that all files contain proper licensing information."""
 
 
 import json
 import optparse
@@ skipping 168 matching lines @@
     'third_party/devscripts': [
         'GPL (v2 or later)',
     ],
     'third_party/expat/files/lib': [  # http://crbug.com/98121
         'UNKNOWN',
     ],
     'third_party/ffmpeg': [
         'GPL',
         'GPL (v2)',
         'GPL (v2 or later)',
+        'GPL (v3 or later)',
         'UNKNOWN',  # http://crbug.com/98123
     ],
     'third_party/fontconfig': [
         # https://bugs.freedesktop.org/show_bug.cgi?id=73401
         'UNKNOWN',
     ],
     'third_party/freetype2': [ # http://crbug.com/177319
         'UNKNOWN',
     ],
     'third_party/hunspell': [  # http://crbug.com/98134
@@ skipping 337 matching lines @@
                            action='store_true',
                            default=False,
                            help='Ignore path-specific license whitelist.')
   option_parser.add_option('--json', help='Path to JSON output file')
   options, args = option_parser.parse_args()
   return check_licenses(options, args)
 
 
 if '__main__' == __name__:
   sys.exit(main())