Reduce the number of flush entry points

Change-Id: I02397851f73b7ef78e0ddfa682a8c812dec31eb8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206395
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
4 files changed