Add headless_browsertests with --enable-features=NetworkService

Bug: 838291
Change-Id: I02f10d1ab707f5012a56c2dc805b86ee0c0537cf
Reviewed-on: https://chromium-review.googlesource.com/c/1278994
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599454}
2 files changed