Add --disable-audio to media_basic_playback pyauto test.

chrome/test/functional/media/media_basic_playback.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.
 
 """Basic playback test.  Checks playback, seek, and replay based on events.
 
 This test uses the bear videos from the test matrix in h264, vp8, and theora
 formats.
 """
@@ skipping 16 matching lines @@
                  'bear_silent.ogv', 'bear_silent.webm']]
 
 # Expected events for the first iteration and every iteration thereafter.
 _EXPECTED_EVENTS_0 = [('ended', 2), ('playing', 2), ('seeked', 1)]
 _EXPECTED_EVENTS_n = [('abort', 1), ('emptied', 1)] + _EXPECTED_EVENTS_0
 
 
 class MediaConstrainedNetworkPerfTest(pyauto.PyUITest):
   """PyAuto test container.  See file doc string for more information."""
 
+  def ExtraChromeFlags(self):
+    """Run with --disable-audio to avoid issues with bots with no audio output.
+
+    TODO(shadi): Remove extra flag once issue (crbug.com/120749) is resolved.
+    """
+    return pyauto.PyUITest.ExtraChromeFlags(self) + ['--disable-audio']
+
   def testBasicPlaybackMatrix(self):
     """Launches HTML test which plays each video until end, seeks, and replays.
 
     Specifically ensures that after the above sequence of events, the following
     are true:
 
         1. The first video has only 2x playing, 2x ended, and 1x seeked events.
         2. Each subsequent video additionally has 1x abort and 1x emptied due to
            switching of the src attribute.
         3. video.currentTime == video.duration for each video.
@@ skipping 21 matching lines @@
         else:
           self.assertEqual(counts, _EXPECTED_EVENTS_n)
       except:
         logging.debug(
             'Test failed with events: %s', self.GetDOMValue("events.join(',')"))
         raise
 
 
 if __name__ == '__main__':
   pyauto_media.Main()