Reland "Remove ARC from tools lib."

This is a reland of 4c4c80fa12649e2512e4601d0a19f19f8907d6ca

Original change's description:
> Remove ARC from tools lib.
>
> Trying this in baby steps to manage leaks better.
>
> Change-Id: Id8597ba236c752bcbf1c7ec94f6c1021e636d547
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372556
> Commit-Queue: Jim Van Verth <jvanverth@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Adlai Holler <adlai@google.com>

Change-Id: Ib5c949ee9e8ac9f47de1991297aec718f3185424
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/373616
Reviewed-by: Adlai Holler <adlai@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index 738f1b3..4f7ca64 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -6,6 +6,9 @@
 
 Milestone 90
 ------------
+  * Renamed use of sk_cf_obj in external Metal types to sk_cfp.
+    https://review.skia.org/372556
+
   * GrDirectContext::ComputeImageSize() is removed. Use SkImage::textureSize() instead.
     https://review.skia.org/368621
     https://review.skia.org/369317