Just to update:

Same issue still seen on mac 64 beta of continuous builder.

Link to the builder:
-------------------
https://uberchromegw.corp.google.com/i/official.desktop.continuous/builders/mac64%20beta/builds/6872

link to error log:
-----------------
https://logs.chromium.org/logs/chrome/bb/official.desktop.continuous/mac64_beta/6872/+/recipes/steps/unit_tests/0/stdout

Could some one from dev team please take a look.
Thanks..!

Just to update:

Same issue still seen on Mac64 - Canary of Official builder.

Link to the builder:
-------------------
https://uberchromegw.corp.google.com/i/official.desktop/builders/mac64/builds/3778

link to error log:
-----------------
https://logs.chromium.org/logs/chrome/bb/official.desktop/mac64/3778/+/recipes/steps/unit_tests/0/stdout

Thanks!

Mac triage: to avi@ - can you take a peek at this failure?

I genuinely am not understanding HistoryMenuBridgeTest.GetFaviconForHistoryItem and HistoryMenuBridgeTest.GotFaviconData. They both call HistoryMenuBridge::GetFaviconForHistoryItem which *starts a background task*. They then test some things and then *end*, racing the task, which may or may not finish before the HistoryMenuBridge that's instantiated for the test is torn down!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/019667bdfb7f4c9c89bd7e9fce80c0193633f141

commit 019667bdfb7f4c9c89bd7e9fce80c0193633f141
Author: Avi Drissman <avi@chromium.org>
Date: Wed Jan 02 19:57:36 2019

Avoid races in HistoryMenuBridge.

BUG= 916749 

Change-Id: Ideb4f53009923138676063e2186332c0b4d147a2
Reviewed-on: https://chromium-review.googlesource.com/c/1393021
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619460}
[modify] https://crrev.com/019667bdfb7f4c9c89bd7e9fce80c0193633f141/chrome/browser/ui/cocoa/history_menu_bridge_unittest.mm

That should deflake the test.