The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aec41dcbdec84a6a9302a68587e19bfc85a146b6

commit aec41dcbdec84a6a9302a68587e19bfc85a146b6
Author: Xida Chen <xidachen@chromium.org>
Date: Thu Aug 16 18:05:18 2018

Disable MaterialHistoryItemTest.All on Mac

TBR=wjmaclean@chromium.org
NOTRY=true

Bug:  874976 
Change-Id: I85a635544c5305bce8bb80ca3b2fedc50fd5a4fd
Reviewed-on: https://chromium-review.googlesource.com/1178310
Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583730}
[modify] https://crrev.com/aec41dcbdec84a6a9302a68587e19bfc85a146b6/chrome/test/data/webui/md_history/md_history_browsertest.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/68220b123f97ce2e06bbc93cbf5e55c64587577b

commit 68220b123f97ce2e06bbc93cbf5e55c64587577b
Author: Thomas Anderson <thomasanderson@chromium.org>
Date: Thu Aug 16 18:15:44 2018

Revert "Disable MaterialHistoryItemTest.All on Mac"

This reverts commit aec41dcbdec84a6a9302a68587e19bfc85a146b6.

Reason for revert: Breaks build on Win Builder (dbg)
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win%20Builder%20%28dbg%29/50751

Original change's description:
> Disable MaterialHistoryItemTest.All on Mac
> 
> TBR=wjmaclean@chromium.org
> NOTRY=true
> 
> Bug:  874976 
> Change-Id: I85a635544c5305bce8bb80ca3b2fedc50fd5a4fd
> Reviewed-on: https://chromium-review.googlesource.com/1178310
> Reviewed-by: Xida Chen <xidachen@chromium.org>
> Commit-Queue: Xida Chen <xidachen@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#583730}

TBR=xidachen@chromium.org,wjmaclean@chromium.org

Change-Id: Iddba28b5f6992f94c5166192f799344065e2a274
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  874976 
Reviewed-on: https://chromium-review.googlesource.com/1178501
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583735}
[modify] https://crrev.com/68220b123f97ce2e06bbc93cbf5e55c64587577b/chrome/test/data/webui/md_history/md_history_browsertest.js

Started an alternative fix, that will filter this test out only in polymer2 browser tests, here: https://crrev.com/c/1178639

Note that if this test is failing in browser_tests and not just webui_polymer2_browser_tests, that would indicate a regression.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dd3084b16bc7335c3cb1d40841bf94586c9eaeb5

commit dd3084b16bc7335c3cb1d40841bf94586c9eaeb5
Author: Xida Chen <xidachen@chromium.org>
Date: Thu Aug 16 21:41:39 2018

Disable MaterialHistoryItemTest.All on Mac

TBR=wjmaclean@chromium.org

Bug:  874976 
Change-Id: I6973e2de0fb52dbfe5cec8319a02507736603243
Reviewed-on: https://chromium-review.googlesource.com/1178476
Reviewed-by: Xida Chen <xidachen@chromium.org>
Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583825}
[modify] https://crrev.com/dd3084b16bc7335c3cb1d40841bf94586c9eaeb5/chrome/test/data/webui/md_history/md_history_browsertest.js

FYI, modifying CL in comment 2 to revert the change in comment 4. We don't want to disable this in general, only in webui_polymer2_browser_tests.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/10c0c8c01c8eea683478dabc3e3308edc3f698c4

commit 10c0c8c01c8eea683478dabc3e3308edc3f698c4
Author: rbpotter <rbpotter@chromium.org>
Date: Fri Aug 17 04:10:05 2018

WebUI Polymer2: Filter out material history item test

The test is failing (flaky?) on Mac 10.12.

Bug:  874976 
Change-Id: I913c6d39d7650e8298cd83eb2236f0f0d027f5d1
Reviewed-on: https://chromium-review.googlesource.com/1178639
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583956}
[modify] https://crrev.com/10c0c8c01c8eea683478dabc3e3308edc3f698c4/chrome/test/data/webui/md_history/md_history_browsertest.js
[modify] https://crrev.com/10c0c8c01c8eea683478dabc3e3308edc3f698c4/testing/buildbot/filters/webui_polymer2_browser_tests.filter

Marking this as blocking the main bug, and unassigning myself as I do not have a Mac to try to reproduce this issue locally.

Actually, it appears this was fixed already by aee@, who removed it from the filter file it was added to in comment 6.