See some CQ build failures with these error message in HWTest [bvt-cq]:


07/10 21:26:41.621 WARNI|              test:0637| The test failed with the following exception
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 631, in _exec
    _call_test_function(self.execute, *p_args, **p_dargs)
  File "/usr/local/autotest/common_lib/test.py", line 837, in _call_test_function
    raise error.UnhandledTestFail(e)
UnhandledTestFail: Unhandled DBusException: org.freedesktop.DBus.Error.ServiceUnknown: The name org.chromium.cras was not provided by any .service files
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 831, in _call_test_function
    return func(*args, **dargs)
  File "/usr/local/autotest/common_lib/test.py", line 495, in execute
    dargs)
  File "/usr/local/autotest/common_lib/test.py", line 362, in _call_run_once_with_retry
    postprocess_profiled_run, args, dargs)
  File "/usr/local/autotest/common_lib/test.py", line 400, in _call_run_once
    self.run_once(*args, **dargs)
  File "/usr/local/autotest/tests/audio_Microphone/audio_Microphone.py", line 50, in run_once
    cras_device_name = cras_utils.get_selected_input_device_name()
  File "/usr/local/autotest/cros/audio/cras_utils.py", line 345, in get_selected_input_device_name
    nodes = get_cras_nodes()
  File "/usr/local/autotest/cros/audio/cras_utils.py", line 194, in get_cras_nodes
    return get_cras_control_interface().GetNodes()
  File "/usr/local/autotest/cros/audio/cras_utils.py", line 184, in get_cras_control_interface
    cras_object = bus.get_object('org.chromium.cras', '/org/chromium/cras')
  File "/usr/local/lib/python2.7/site-packages/dbus/bus.py", line 241, in get_object
    follow_name_owner_changes=follow_name_owner_changes)
  File "/usr/local/lib/python2.7/site-packages/dbus/proxies.py", line 248, in __init__
    self._named_service = conn.activate_name_owner(bus_name)
  File "/usr/local/lib/python2.7/site-packages/dbus/bus.py", line 180, in activate_name_owner
    self.start_service_by_name(bus_name)
  File "/usr/local/lib/python2.7/site-packages/dbus/bus.py", line 278, in start_service_by_name
    'su', (bus_name, flags)))
  File "/usr/local/lib/python2.7/site-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
DBusException: org.freedesktop.DBus.Error.ServiceUnknown: The name org.chromium.cras was not provided by any .service files


Suffered Build:
https://luci-milo.appspot.com/buildbot/chromeos/edgar-paladin/3438
https://luci-milo.appspot.com/buildbot/chromeos/eve-paladin/3627
https://luci-milo.appspot.com/buildbot/chromeos/sentry-paladin/3558
https://luci-milo.appspot.com/buildbot/chromeos/veyron_speedy-paladin/9267


Besides, all of these four builds also have "FAIL: Android did not boot!" error (issue 862415).
Not sure if they are related.