Adding HTML5 track(caption) test case in PyAuto media functional tests.

chrome/test/functional/PYAUTO_TESTS

 # Copyright (c) 2011 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.
 #
 # This file lists the pyauto tests that run as a part of the functional test
 # suite.
 #
 # Tests can be enabled on a per-platform basis. Tests not listed here will
 # not be run.
 #
@@ skipping 340 matching lines @@
        'media.media_playbacktime',
        'media.media_perf',
        'media.media_fps',
      ],
   },
 
   # HTML5 media functional tests.   
   'AV_FUNC': {
      'linux': [
        'media.media_event_simple_test',
-       'media.media_track',
+       'media.media_event_track',
      ],
   },
 }