Don't execute onFlush op lists until after GPU data is uploaded

Bug: skia:
Change-Id: I2ea15f67466761ebd24b9d4a8eb51cd2d452be3c
Reviewed-on: https://skia-review.googlesource.com/54942
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
1 file changed