These bots have been failing for a while, often (at least recently) with this failure along with  issue 714803 .

telemetry.web_perf.timeline_based_page_test_unittest.TimelineBasedPageTestTest.testTraceCaptureUponFailure

04/24 12:58:00.718 INFO |run_chromeos_tests:0052| [1084/1084] telemetry.web_perf.timeline_based_page_test_unittest.TimelineBasedPageTestTest.testTraceCaptureUponFailure failed unexpectedly 0.0009s:
04/24 12:58:00.719 INFO |run_chromeos_tests:0052|   Traceback (most recent call last):
04/24 12:58:00.719 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/web_perf/timeline_based_page_test_unittest.py", line 55, in setUp
04/24 12:58:00.720 INFO |run_chromeos_tests:0052|       browser_test_case.teardown_browser()
04/24 12:58:00.720 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/testing/browser_test_case.py", line 62, in teardown_browser
04/24 12:58:00.720 INFO |run_chromeos_tests:0052|       current_browser.Close()
04/24 12:58:00.721 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/browser/browser.py", line 268, in Close
04/24 12:58:00.721 INFO |run_chromeos_tests:0052|       self._browser_backend.Close()
04/24 12:58:00.721 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
04/24 12:58:00.722 INFO |run_chromeos_tests:0052|       return func(*args, **kwargs)
04/24 12:58:00.722 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/cros_browser_backend.py", line 183, in Close
04/24 12:58:00.723 INFO |run_chromeos_tests:0052|       py_utils.WaitFor(lambda: not self._IsCryptohomeMounted(), 180)
04/24 12:58:00.723 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/common/py_utils/py_utils/__init__.py", line 113, in WaitFor
04/24 12:58:00.723 INFO |run_chromeos_tests:0052|       res = condition()
04/24 12:58:00.724 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/cros_browser_backend.py", line 183, in <lambda>
04/24 12:58:00.724 INFO |run_chromeos_tests:0052|       py_utils.WaitFor(lambda: not self._IsCryptohomeMounted(), 180)
04/24 12:58:00.724 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
04/24 12:58:00.725 INFO |run_chromeos_tests:0052|       return func(*args, **kwargs)
04/24 12:58:00.725 INFO |run_chromeos_tests:0052|     File "/usr/local/telemetry/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/cros_browser_backend.py", line 244, in _IsCryptohomeMounted
04/24 12:58:00.725 INFO |run_chromeos_tests:0052|       return self._cri.IsCryptohomeMounted(username, self._is_guest)
04/24 12:58:00.726 INFO |run_chromeos_tests:0052|   AttributeError: 'NoneType' object has no attribute 'IsCryptohomeMounted'