Tests affected: 

  - battor.power_cases_no_chrome_trace
  - battor.power_cases_no_chrome_trace.reference

On the Android Power Nexus 5X Perf bot (https://luci-milo.appspot.com/buildbot/chromium.perf.fyi/Android%20Power%20Nexus%205X%20Perf%20%281%29/) on the FYI waterfall, these two BattOr benchmarks seem to be failing reliably due to a TIMEOUT error. The stack trace looks like this:

Traceback (most recent call last):
  RunBenchmark at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:327
    benchmark.ShouldTearDownStateAfterEachStorySetRun())
  Run at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:227
    _RunStoryAndProcessErrorIfNeeded(story, results, state, test)
  _RunStoryAndProcessErrorIfNeeded at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:78
    test.WillRunStory(state.platform)
  WillRunStory at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/web_perf/timeline_based_measurement.py:274
    platform.tracing_controller.StartTracing(self._tbm_options.config)
  StartTracing at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/core/tracing_controller.py:43
    self._tracing_controller_backend.StartTracing(tracing_config, timeout)
  StartTracing at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/internal/platform/tracing_controller_backend.py:91
    if agent.StartAgentTracing(config, timeout):
  StartAgentTracing at /b/rr/tmp6Epbxe/w/src/third_party/catapult/telemetry/telemetry/internal/platform/tracing_agent/battor_tracing_agent.py:73
    self._battor.StartTracing()
  StartTracing at /b/rr/tmp6Epbxe/w/src/third_party/catapult/common/battor/battor/battor_wrapper.py:155
    self._SendBattorCommand(self._START_TRACING_CMD)
  _SendBattorCommand at /b/rr/tmp6Epbxe/w/src/third_party/catapult/common/battor/battor/battor_wrapper.py:269
    'Outputted: %s' % (cmd, status))
BattorError: BattOr did not complete command 'StartTracing' correctly.
Outputted: [0913/225933:FATAL:battor_agent_bin.cc(88)] Fatal error when communicating with the BattOr: TIMEOUT

I have no idea why these benchmarks would be repeatedly timing out when starting tracing, but the other BattOr tests wouldn't be. We literally have the exact same tests running (and passing), where the only difference is that we don't collect a Chrome trace for these.