Chrome Version: 72.0.3622.0 (Official Build) canary (64
OS: Mac OS 10.14.1

What steps will reproduce the problem?
(1) Run `tools/perf/run_benchmark blink_perf.canvas`


Get the error:
Traceback (most recent call last):
  RunBenchmark at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:369
    expectations=expectations, max_num_values=benchmark.MAX_NUM_VALUES)
  Run at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:217
    test, finder_options.Copy(), story_set)
  traced_function at /Users/aaronhk/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
    return func(*args, **kwargs)
  __init__ at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/page/shared_page_state.py:55
    self._test, finder_options)
  traced_function at /Users/aaronhk/chrome/src/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py:52
    return func(*args, **kwargs)
  _GetPossibleBrowser at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/page/shared_page_state.py:107
    enabled, msg = decorators.IsEnabled(test, possible_browser)
  IsEnabled at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/decorators.py:245
    should_skip, msg = ShouldSkip(test, possible_browser)
  ShouldSkip at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/decorators.py:316
    platform_attributes = _PlatformAttributes(possible_browser)
  _PlatformAttributes at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/decorators.py:363
    possible_browser.platform.GetOSVersionName(),
  GetOSVersionName at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/core/platform.py:158
    return self._platform_backend.GetOSVersionName()
  Cacher at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/decorators.py:35
    cacher.__cache[key] = obj(*args, **kwargs)
  GetOSVersionName at /Users/aaronhk/chrome/src/third_party/catapult/telemetry/telemetry/internal/platform/mac_platform_backend.py:132
    raise NotImplementedError('Unknown mac version %s.' % os_version)
NotImplementedError: Unknown mac version 18.2.0.