Add --disable-audio to media_basic_playback pyauto test.

chrome/test/functional/media/media_basic_playback.py

Index: chrome/test/functional/media/media_basic_playback.py
diff --git a/chrome/test/functional/media/media_basic_playback.py b/chrome/test/functional/media/media_basic_playback.py
index cedd567c82c935bd2847e7fee4727d2e386b81e5..3f41c6528fc5692ebb45b024e5922411579e5468 100755
--- a/chrome/test/functional/media/media_basic_playback.py
+++ b/chrome/test/functional/media/media_basic_playback.py
@@ -34,6 +34,13 @@ _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.