Revert "Remove deprecated flush calls."

This reverts commit d8fd0bf5749c62302eb1d1c9f4eaab151d839341.

Reason for revert: chrome roll

Original change's description:
> Remove deprecated flush calls.
> 
> Bug: skia:10118
> Change-Id: I13758b5416784c296b8b5be9f3228230ac1be05f
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290540
> Commit-Queue: Greg Daniel <egdaniel@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=egdaniel@google.com,bsalomon@google.com

Change-Id: I49d35cdb258e632f645974c5ec62075d3392efe0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:10118
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290834
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
7 files changed