The VariationsService is only created in official builds:

https://cs.chromium.org/chromium/src/components/variations/service/variations_service.cc?rcl=f7a44e1558455d493b4d519eee318f51e5fe262a&l=532

If there is no VariationsService, then CreateTrialsFromSeed is not called:

https://cs.chromium.org/chromium/src/chrome/browser/chrome_browser_main.cc?rcl=f58f2b25669173bf3032225603725a2469e01ff1&l=740

Alexei, why is this tied to official builds? To improve test coverage in unofficial builds, could we create the VariationsService, but treat all experiments as disabled?

It's not enabled for official builds because Chromium builds shouldn't talk to Google for experiments. I agree it's not optimal in terms of testing. We could still have the object but just not do the fetching.

"We could still have the object but just not do the fetching."

One of my later CLs moves most of SetupFieldTrials() into VariationsFieldTrialCreator. That could be a good time to rework this.

Changing title since this is tracking specifically having VariationsService be tested by Chromium builds. Kyle has a CL in the works along these lines, so changing owner to him.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a913c84885430612de2a5984c7d6cb21d485cb63

commit a913c84885430612de2a5984c7d6cb21d485cb63
Author: Kyle Milka <kmilka@google.com>
Date: Thu Jul 27 08:35:56 2017

Prevent non-official builds from fetching from the variations server.

This CL restricts variations seed fetching to only official Chrome
builds. This will allow the CQ to catch bugs related to the
VariationsService object for all Chromium builds, but prevent Chromium
from fetching from the variations server.

Bug:  746019 
Change-Id: I897844b4ca2cf54c212142c68ac29652df70ee84
Reviewed-on: https://chromium-review.googlesource.com/583716
Commit-Queue: Kyle Milka <kmilka@google.com>
Reviewed-by: Alexei Svitkine (OOO July28-Aug6) <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489884}
[modify] https://crrev.com/a913c84885430612de2a5984c7d6cb21d485cb63/components/variations/service/variations_service.cc
[modify] https://crrev.com/a913c84885430612de2a5984c7d6cb21d485cb63/components/variations/service/variations_service_unittest.cc