According to sheriff-o-matic, Mac10.10 Tests has [49 out of the last 50 builds have failed] and Mac10.12 Tests [47 out of the last 47 builds have failed], so it seems like a pretty consistent failure.

Link to regression range: https://chromium.googlesource.com/chromium/src/+log/458236cb920e35864c7983b2b7e9c301a29edde9..8997722518cd27d1c7fea4601ae9c94faa413a3f?pretty=fuller&n=

Not sure what could be causing this, but this commit was listed in the third_party/catapult autoroll (https://chromium.googlesource.com/chromium/src/+/bb11cbc66e56a475bdf0f5bf3d962cf80c3afe27):

2018-10-11 chiniforooshan@chromium.org Telemetry: migrate frame_times & percentage_smooth

chiniforooshan@, are you able to provide any insight on whether these Mac failures are related to your patch? Thanks!

+1 catapult-roll causes this failure.

Looking at
https://chromium.googlesource.com/catapult.git/+/0480f8caeb27101608c99e4df2f686d6697551f4%5E%21/
'frame_times' was removed from stats:

diff --git a/telemetry/telemetry/web_perf/metrics/smoothness_unittest.py b/telemetry/telemetry/web_perf/metrics/smoothness_unittest.py
index aa1cd76..49ee9fb 100644
--- a/telemetry/telemetry/web_perf/metrics/smoothness_unittest.py
+++ b/telemetry/telemetry/web_perf/metrics/smoothness_unittest.py
@@ -11,10 +11,10 @@
 
 class _MockRenderingStats(object):
 
-  stats = ['refresh_period', 'frame_timestamps', 'frame_times', 'paint_times',
-           'painted_pixel_counts', 'record_times', 'recorded_pixel_counts',
-           'input_event_latency', 'frame_queueing_durations',
-           'main_thread_scroll_latency', 'gesture_scroll_update_latency']
+  stats = ['paint_times', 'painted_pixel_counts', 'record_times',
+           'recorded_pixel_counts', 'input_event_latency',
+           'frame_queueing_durations', 'main_thread_scroll_latency',
+           'gesture_scroll_update_latency']

However, tools/perf/measurements/smoothness_unittest.py is still using 'frame_times':

  def testSmoothness(self):
    ps = self.CreateStorySetFromFileInUnittestDataDir('scrollable_page.html')
    measurement = smoothness.Smoothness()
    results = self.RunMeasurement(measurement, ps, options=self._options)
    self.assertFalse(results.had_failures)
    stat = rendering_util.ExtractStat(results)

    self.assertGreater(stat['frame_times'].mean, 0)

Disabled the test on mac: https://chromium-review.googlesource.com/c/chromium/src/+/1280242

This bug doesn't look different from 895238