Update SkSurface's cached image ownership handling to sk_sp

Change-Id: I9dca3d355bfe39211cb5054a5834d9c1750d8152
Reviewed-on: https://skia-review.googlesource.com/7780
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
2 files changed