Remove legacy async read pixels APIs.

Chrome is now using the newer version.

Bug: skia:8962
Change-Id: I8c38bde63e1e032281d19b0cc7cb8cf301061a9e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/251198
Commit-Queue: Greg Daniel <egdaniel@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index af2be25..5e3a364 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -8,6 +8,9 @@
 
 <Insert new notes here- top is most recent.>
 
+  * Remove old async read pixels APIs
+    https://review.skia.org/251198
+
 * * *
 
 Milestone 79