cgrant@ your CL https://chromium-review.googlesource.com/c/chromium/src/+/1331632 is the only one that would seem likely. Please take a look.

If you are convinced that this is unrelated, please assign back to me and I'll get someone else to look.

--

1-time strangeness in https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Android%20Release%20%28Nexus%205X%29/12727

webgl_conformance_tests on Android device Nexus 5X Run on OS: 'Android'
Max shard duration: 0:17:22.328847 (shard #2)
Min shard duration: 0:05:48.015349 (shard #3)
Total tests: 777
* Passed: 768 (768 expected, 0 unexpected)
* Skipped: 9 (9 expected, 0 unexpected)
* Failed: 0 (0 expected, 0 unexpected)
* Flaky: 0 (0 expected, 0 unexpected)

That all looks good. But: the test is marked as failed. Something went wrong at the end of the test:

...elided dump...

                 LOCK_ACQUISITION_TIMEOUT). <traceback object at 0x7f23fb450560>

Traceback (most recent call last):
  <module> at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/testing/run_browser_tests.py:404
    ret_code = RunTests(sys.argv[1:])
  RunTests at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/testing/run_browser_tests.py:346
    ret, _, _ = runner.run()
  run at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/runner.py:200
    result_set, test_set.copy(), all_tests)
  _run_tests at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/runner.py:510
    self._run_one_set(self.stats, result_set, test_set)
  _run_one_set at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/runner.py:552
    test_set.isolated_tests, 1)
  _run_list at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/runner.py:578
    _setup_process, _teardown_process)
  make_pool at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/pool.py:28
    return _AsyncPool(host, jobs, callback, context, pre_fn, post_fn)
  __init__ at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/pool.py:188
    self.context_after_pre = pre_fn(self.host, 1, self.context)
  _setup_process at /b/swarming/w/ir/third_party/catapult/third_party/typ/typ/runner.py:854
    child.context_after_setup = child.setup_fn(child, child.context)
  _SetUpProcess at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/testing/run_browser_tests.py:394
    context.test_class.SetUpProcess()
  SetUpProcess at /b/swarming/w/ir/content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:306
    cls.SetupWebGLBrowserArgs([])
  SetupWebGLBrowserArgs at /b/swarming/w/ir/content/test/gpu/gpu_tests/webgl_conformance_integration_test.py:291
    cls.CustomizeBrowserArgs(browser_args)
  CustomizeBrowserArgs at /b/swarming/w/ir/content/test/gpu/gpu_tests/gpu_integration_test.py:73
    cls.SetBrowserOptions(cls._finder_options)
  SetBrowserOptions at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/testing/serially_executed_browser_test_case.py:70
    cls._browser_to_create = browser_finder.FindBrowser(browser_options)
  Cacher at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/decorators.py:35
    cacher.__cache[key] = obj(*args, **kwargs)
  FindBrowser at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/internal/browser/browser_finder.py:117
    chosen_browser.UpdateExecutableIfNeeded()
  Cacher at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/decorators.py:35
    cacher.__cache[key] = obj(*args, **kwargs)
  UpdateExecutableIfNeeded at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/internal/backends/chrome/android_browser_finder.py:291
    self.platform.InstallApplication(self._local_apk)
  InstallApplication at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/core/platform.py:244
    return self._platform_backend.InstallApplication(application)
  InstallApplication at /b/swarming/w/ir/third_party/catapult/telemetry/telemetry/internal/platform/android_platform_backend.py:377
    self._device.Install(application)
  timeout_retry_wrapper at /b/swarming/w/ir/third_party/catapult/devil/devil/android/decorators.py:57
    retry_if_func=retry_if_func)
  Run at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/timeout_retry.py:158
    error_log_func=error_log_func)
  JoinAll at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/reraiser_thread.py:198
    self._JoinAll(watcher, timeout)
  _JoinAll at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/reraiser_thread.py:170
    thread.ReraiseIfException()
  run at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/reraiser_thread.py:93
    self._ret = self._func(*self._args, **self._kwargs)
  <lambda> at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/timeout_retry.py:151
    child_thread = reraiser_thread.ReraiserThread(lambda: func(*args, **kwargs),
  impl at /b/swarming/w/ir/third_party/catapult/devil/devil/android/decorators.py:47
    return f(*args, **kwargs)
  Install at /b/swarming/w/ir/third_party/catapult/devil/devil/android/device_utils.py:881
    reinstall=reinstall, permissions=permissions)
  _InstallInternal at /b/swarming/w/ir/third_party/catapult/devil/devil/android/device_utils.py:936
    package_name = base_apk.GetPackageName()
  GetPackageName at /b/swarming/w/ir/third_party/catapult/devil/devil/android/apk_helper.py:193
    manifest_info = self._GetManifest()
  _GetManifest at /b/swarming/w/ir/third_party/catapult/devil/devil/android/apk_helper.py:238
    self._manifest = _ParseManifestFromApk(self._apk_path)
  _ParseManifestFromApk at /b/swarming/w/ir/third_party/catapult/devil/devil/android/apk_helper.py:49
    aapt_output = aapt.Dump('xmltree', apk_path, 'AndroidManifest.xml')
  Dump at /b/swarming/w/ir/third_party/catapult/devil/devil/android/sdk/aapt.py:43
    return _RunAaptCmd(['dump', what, apk] + assets).splitlines()
  _RunAaptCmd at /b/swarming/w/ir/third_party/catapult/devil/devil/android/sdk/aapt.py:24
    cmd = [_aapt_path.read()] + args
  read at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/lazy/weak_constant.py:39
    self._val = initializer_thread.GetReturnValue()
  GetReturnValue at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/reraiser_thread.py:86
    self.ReraiseIfException()
  run at /b/swarming/w/ir/third_party/catapult/devil/devil/utils/reraiser_thread.py:93
    self._ret = self._func(*self._args, **self._kwargs)
  <lambda> at /b/swarming/w/ir/third_party/catapult/devil/devil/android/sdk/aapt.py:12
    _aapt_path = lazy.WeakConstant(lambda: build_tools.GetPath('aapt'))
  GetPath at /b/swarming/w/ir/third_party/catapult/devil/devil/android/sdk/build_tools.py:25
    return devil_env.config.FetchPath(build_tool)
  FetchPath at /b/swarming/w/ir/third_party/catapult/devil/devil/devil_env.py:175
    return self._dm.FetchPath(dependency, GetPlatform(arch, device))
  FetchPath at /b/swarming/w/ir/third_party/catapult/dependency_manager/dependency_manager/manager.py:130
    path, _ = self.FetchPathWithVersion(dependency, platform)
  FetchPathWithVersion at /b/swarming/w/ir/third_party/catapult/dependency_manager/dependency_manager/manager.py:93
    path = dependency_info.GetRemotePath()
  GetRemotePath at /b/swarming/w/ir/third_party/catapult/dependency_manager/dependency_manager/dependency_info.py:84
    return self._cloud_storage_info.GetRemotePath()
  GetRemotePath at /b/swarming/w/ir/third_party/catapult/dependency_manager/dependency_manager/cloud_storage_info.py:80
    self._cs_hash)
  GetIfHashChanged at /b/swarming/w/ir/third_party/catapult/common/py_utils/py_utils/cloud_storage.py:400
    with _FileLock(download_path):
  __enter__ at /b/swarming/w/ir/.swarming_module/lib/python2.7/contextlib.py:17
    return self.gen.next()
  _FileLock at /b/swarming/w/ir/third_party/catapult/common/py_utils/py_utils/cloud_storage.py:272
    LOCK_ACQUISITION_TIMEOUT)
  WaitFor at /b/swarming/w/ir/third_party/catapult/common/py_utils/py_utils/__init__.py:150
    (timeout, GetConditionString()))
TimeoutException: Timed out while waiting 10s for py_utils.WaitFor(lambda: _AttemptPseudoLockAcquisition(pseudo_lock_path,
                                                         pseudo_lock_fd_return),
                   LOCK_ACQUISITION_TIMEOUT).

Locals:
  GetConditionString       : <function GetConditionString at 0x7f23fb986ed8>
  condition                : <function <lambda> at 0x7f23fb986de8>
  elapsed_time             : 10.893241167068481
  last_output_elapsed_time : 10.893241167068481
  last_output_time         : 1542232785.321966
  now                      : 1542232796.215207
  poll_interval            : 1.0893241167068481
  res                      : False
  start_time               : 1542232785.321966
  timeout                  : 10

(INFO) 2018-11-14 21:59:57,440 android_power_monitor_controller._ReenableChargingIfNeeded:14  Charging status checked at exit.
**Non zero exit code**
If you don't see any error stack, this could have been a native crash. Consider installing faulthandler (https://faulthandler.readthedocs.io/) for more useful error message