This test (and others) seems to first call InitServices and kick of creating services, and afterwards tries to call ScopedFeatureList::InitAndEnableFeature, which races with some of these services trying to check if a feature is enabled.

"Caused" by https://chromium-review.googlesource.com/c/chromium/src/+/1257912 but this was always a time bomb waiting to happen...

ExtensionServiceTestSupervised.ExtensionApprovalBeforeInstallation is flaky.

Findit has detected 11 new flake occurrences of this test. List
of all flake occurrences can be found at:
https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyYQsSBUZsYWtlIlZjaHJvbWl1bUB1bml0X3Rlc3RzQEV4dGVuc2lvblNlcnZpY2VUZXN0U3VwZXJ2aXNlZC5FeHRlbnNpb25BcHByb3ZhbEJlZm9yZUluc3RhbGxhdGlvbgw.

Since this test is still flaky, this issue has been moved back onto the Sheriff
Bug Queue if it's not already there.

If the result above is wrong, please file a bug using this link:
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%20Detection%20-%20Wrong%20result%20for%20ExtensionServiceTestSupervised.ExtensionApprovalBeforeInstallation&comment=Link%20to%20flake%20occurrences%3A%20https://findit-for-me.appspot.com/flake/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyYQsSBUZsYWtlIlZjaHJvbWl1bUB1bml0X3Rlc3RzQEV4dGVuc2lvblNlcnZpY2VUZXN0U3VwZXJ2aXNlZC5FeHRlbnNpb25BcHByb3ZhbEJlZm9yZUluc3RhbGxhdGlvbgw

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/+/a68eea5eb428d5f7c1aad7ced339016251984e36

commit a68eea5eb428d5f7c1aad7ced339016251984e36
Author: Mikel Astiz <mastiz@chromium.org>
Date: Fri Oct 05 07:59:14 2018

Fix TSAN flakiness due to late ScopedFeatureList

Feature toggles cannot change during runtime, so let's make sure the
final values are fixed before a profile is created for tests. This fixes
flakiness in TSAN bots due to recent unrelated changes, where a
KeyedService's backend thread reads a feature toggle (although the
feature is unrelated to this test suite).

TBR=rockot@chromium.org

Bug:  891906 
Change-Id: I385c8d5ff38c660d84465cbaaa1bcbeca6b9482a
Reviewed-on: https://chromium-review.googlesource.com/c/1264161
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597026}
[modify] https://crrev.com/a68eea5eb428d5f7c1aad7ced339016251984e36/chrome/browser/extensions/extension_service_sync_unittest.cc

I'll assume the patch above fixes the issue, let's reopen if that's not the case.