Findit identified the culprit r552597 with confidence 100.0% in the config "chromium.memory / Linux ChromiumOS MSan Tests"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVysQELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJ7Y2hyb21pdW0ubWVtb3J5L0xpbnV4IENocm9taXVtT1MgTVNhbiBUZXN0cy82ODIzL2Jyb3dzZXJfdGVzdHMvVjJWaVZtbGxkMVJsYzNSekwxZGxZbFpwWlhkVVpYTjBMa0YxZEc5U1pYTnBlbVZOWlhOellXZGxjeTh3DAsSE01hc3RlckZsYWtlQW5hbHlzaXMYAQw


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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2a4b17a43824f510d164393b8782973534c943af

commit 2a4b17a43824f510d164393b8782973534c943af
Author: Eric Karl <ericrk@chromium.org>
Date: Sun Apr 22 11:00:29 2018

Fix Autoresize test flake on MSAN

In rare cases (slowdown due to msan), we may not have a surface ID
for our guest at test start. This can lead to failures as we
expect surface ID to be available and use it to set expectations.

This change causes us to wait for a surface ID if one is not
initially available.

TBR=piman for small test-only fix to flake on bots.

Bug:  835625 
Change-Id: Iaf9a5c79ffe32230f69543c206f89259104cd41d
Reviewed-on: https://chromium-review.googlesource.com/1023592
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552604}
[modify] https://crrev.com/2a4b17a43824f510d164393b8782973534c943af/content/public/test/browser_test_utils.cc