Add CachingHint to makeRasterImage, default to kDisallow

When a client calls makeRasterImage, they're likely to hold on to that
image, and throw away the source (GPU or Lazy). In that situation, it
makes no sense to leave the buffer in the resource cache.

Change-Id: Ic0be8ceb643ed9196526469516be0d200bea42fd
Bug: b/144232910
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263347
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index 8719323..5049993 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -8,6 +8,8 @@
 
 <Insert new notes here- top is most recent.>
 
+  * Added CachingHint to SkImage::makeRasterImage
+
   * Added SkAnimatedImage::getCurrentFrame()
 
   * Add support to create an SkSurface from an MTKView, with delayed acquisition of