Reland "Remove deprecated flush calls."

This reverts commit 5e6d789ce47c8ce474b597073f7580602fcca467.

Reason for revert: Relanding with fix landed in chrome

Original change's description:
> 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>

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

# Not skipping CQ checks because this is a reland.

Bug: skia:10118
Change-Id: Ie24d7845a4ad75f95afe59037ea80a9f38082f13
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290918
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index bcb29c4..106ce20 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -9,6 +9,9 @@
 
   * <insert new release notes here>
 
+  * Remove deprecated version of flush calls on GrContext and SkSurface.
+    https://review.skia.org/2290540
+
   * SkCanvas::drawVertices and drawPatch now support mapping an SkShader without explicit
     texture coordinates. If they're not supplied, the local positions (vertex position or
     patch cubic positions) will be directly used to sample the SkShader.