Revert "Revert "Change image encode api to return sk_sp""

This reverts commit 64778d9f275d8ce3df8f4ab39ff334b7ef5b70d3.

Bug: skia:
Change-Id: I779515ff1e16a40c33890a4bac7a8a07171aadfe
Reviewed-on: https://skia-review.googlesource.com/22261
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
13 files changed