[autoroll] Don't synchronously run Tick() during mode change
[autoroll] Don't synchronously run Tick() during mode change

This will make the mode change UI finish much more quickly and is more
logical: previously a failure in Tick() after the mode changed would
make it seem like the mode change had failed when it had actually
succeeded.

Bug: skia:
Change-Id: If753f3212d61e49052629598a57d70a117b68a1c
Reviewed-on: https://skia-review.googlesource.com/80960
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@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