GitLab

Don't test the other platforms because they now enable the
experimented features by default.

Change-Id: I08fb048e73d4508a4e9155cb1d5e6307db83c47e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095370
Commit-Queue: Vincent Boisselle <vincb@google.com>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749256}