GitLab

Dedicated thread wastes resources and causes races in tests where
it can outlive thread pools used by DnsConfigServicePosix's
SerialWorkers.

Bug: 938126
Change-Id: Ic85c83d164cc26cb218c7e2a0304810c6e0c3be4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1548052
Commit-Queue: Paul Jensen <pauljensen@chromium.org>
Reviewed-by: Eric Orth <ericorth@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650602}