Enable HostResolverImpl unit tests under thread sanitizer.

HostResolverImpl  used to use a worker pool, a global base/ object which
didn't work well with thread sanitizer. It has since been converted to
use the shiny new(ish) base/task_scheduler code, which doesn't have
this issue.

Bug: 334140
Change-Id: Ief61b2d677191baf9b3f8c0170e206d64bc4b0ae
Reviewed-on: https://chromium-review.googlesource.com/c/1450391
Reviewed-by: Eric Roman <[email protected]>
Commit-Queue: Matt Menke <[email protected]>
Cr-Commit-Position: refs/heads/master@{#628444}
1 file changed