[task scheduler] Fix pubsub client
[task scheduler] Fix pubsub client

Always ACK messages.

Bug: skia:
Change-Id: Idd829872ec36aec95db0f6b1fcdbd2e5fccfcf9b
Reviewed-on: https://skia-review.googlesource.com/c/179740
Reviewed-by: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@google.com>
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot