android-only api to reset the fields of a pixelref

BUG=skia:6494

Change-Id: I97c8a93849a13f0c5fd57c8a150ecc2ce363d8f3
Reviewed-on: https://skia-review.googlesource.com/13250
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Reed <reed@google.com>
2 files changed