Findit identified the culprit r580314 with confidence 70.0% in the config "chromium.linux / Linux Tests (dbg)(1)"
based on the flakiness trend:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVyrgELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJ4Y2hyb21pdW0ubGludXgvTGludXggVGVzdHMgKGRiZykoMSkvNzM1NTEvbmV0d29ya19zZXJ2aWNlX2Jyb3dzZXJfdGVzdHMvVkdGaVVtVnpkRzl5WlZSbGMzUXVVbVZ6ZEc5eVpWZHBibVJ2ZDBKdmRXNWtjdz09DAsSE01hc3RlckZsYWtlQW5hbHlzaXMYAQw

If the culprit above is wrong, please file a bug using this link and hit submit:
https://bugs.chromium.org/p/chromium/issues/entry?status=Unconfirmed&labels=Pri-1,Test-Findit-Wrong&components=Tools%3ETest%3EFindit%3EFlakiness&summary=%5BFindit%5D%20Flake%20Analyzer%20-%20Wrong%20result%20for%20TabRestoreTest.RestoreWindowBounds&comment=Link%20to%20Analysis%3A%20https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVyrgELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCJ4Y2hyb21pdW0ubGludXgvTGludXggVGVzdHMgKGRiZykoMSkvNzM1NTEvbmV0d29ya19zZXJ2aWNlX2Jyb3dzZXJfdGVzdHMvVkdGaVVtVnpkRzl5WlZSbGMzUXVVbVZ6ZEc5eVpWZHBibVJ2ZDBKdmRXNWtjdz09DAsSE01hc3RlckZsYWtlQW5hbHlzaXMYAQw

Automatically posted by the findit-for-me app (https://goo.gl/Ot9f7N).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/94006a2aba37481e624cd8128908e3b303f28a52

commit 94006a2aba37481e624cd8128908e3b303f28a52
Author: Kunihiko Sakamoto <ksakamoto@chromium.org>
Date: Mon Aug 06 05:55:50 2018

Revert "[NTP] Adds an experiment for M69 NTP features."

This reverts commit 94558b662d9bf69b2e34bf2d198cad8de74776df.

Reason for revert: Findit thinks this made the following tests flaky:
TabRestoreTest.RestoreWindowBounds ( crbug.com/870945 )
BrowserNavigatorTest.Disposition_NewPopupFromAppPopup (crbug.com/871010)

Original change's description:
> [NTP] Adds an experiment for M69 NTP features.
> 
> Only the first experiment entry gets covered by perf waterfall, so adding
> this item ensures better test coverage. Also, the existing experiment,
> NewTabPageAllBirthday_Enabled, could not be re-used since
> go/revising-finch-configs recommends creating a new experiment when
> changing size or behavior of existing groups.
> 
> Bug: 831910
> Change-Id: I95ebc6f2768fe25d34993c05c71e35c22e2bdcc5
> Reviewed-on: https://chromium-review.googlesource.com/1160925
> Reviewed-by: Steven Holte <holte@chromium.org>
> Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#580314}

TBR=holte@chromium.org,ramyan@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 831910, 870945 ,871010
Change-Id: Ifb86fbc322d939eba40f84b1ee32a21d76361f86
Reviewed-on: https://chromium-review.googlesource.com/1163361
Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580806}
[modify] https://crrev.com/94006a2aba37481e624cd8128908e3b303f28a52/testing/variations/fieldtrial_testing_config.json