cc: Add flag for disabling async worker context.

Helps in debugging the async worker context separately from the gpu
scheduler.

R=piman
BUG=762647

Change-Id: Ia5c1530fd5d65bbd1e2a408e6f38262010839665
Reviewed-on: https://chromium-review.googlesource.com/673027
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503060}
7 files changed