Add struct to wrap all the gpu flush options.

Bug: skia:8802
Change-Id: Ia92807034a8f54067cead59e29c233f91e11f175
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/208674
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
32 files changed