Just encountered this flake. Seems like the maps test failed to load. It only happened once so far.

[1/1] gpu_tests.maps_integration_test.MapsIntegrationTest.Maps_maps failed unexpectedly 80.4444s:
  
  Traceback (most recent call last):
    _RunGpuTest at content/test/gpu/gpu_tests/gpu_integration_test.py:132
      self.RunActualGpuTest(url, *args)
    RunActualGpuTest at content/test/gpu/gpu_tests/maps_integration_test.py:97
      action_runner.WaitForJavaScriptCondition('window.startTest != undefined')
    traced_function at third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
      return func(*args, **kwargs)
    WaitForJavaScriptCondition at third_party/catapult/telemetry/telemetry/internal/actions/action_runner.py:261
      return self._tab.WaitForJavaScriptCondition(*args, **kwargs)
    traced_function at third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
      return func(*args, **kwargs)
    WaitForJavaScriptCondition at third_party/catapult/telemetry/telemetry/internal/browser/web_contents.py:239
      return self._inspector_backend.WaitForJavaScriptCondition(*args, **kwargs)
    traced_function at third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
      return func(*args, **kwargs)
    WaitForJavaScriptCondition at third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_backend.py:302
      e.message + '\n' + debug_message)
  TimeoutException: Timed out while waiting 60s for IsJavaScriptExpressionTrue.
  Console output:
  
  Locals:
    IsJavaScriptExpressionTrue : <function IsJavaScriptExpressionTrue at 0x115fda410>
    condition                  : 'window.startTest != undefined'
    context_id                 : None
    debug_message              : 'Console output:\n'
    e                          : TimeoutException('Timed out while waiting 60s for IsJavaScriptExpressionTrue.',)
    kwargs                     : {}
    timeout                    : 60

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac%20FYI%20Retina%20Release%20%28AMD%29/3468