Revert of Use std::unique_ptr. (patchset #10 id:170001 of https://codereview.chromium.org/1780933003/ )

Reason for revert:
aww jeez, I dropped ps 8...

Original issue's description:
> Use std::unique_ptr.
>
> TBR=reed@google.com
>
> Committed: https://skia.googlesource.com/skia/+/20c1e3abfc681771f73eb19fde7284196e028940
>
> Committed: https://skia.googlesource.com/skia/+/3dd9ed37c24611af86f0fe374bd3698b63f09450
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1780933003
>
> Committed: https://skia.googlesource.com/skia/+/2691d76a06e1af6282f8b3a3140cc93361be10c4

TBR=bungeman@google.com,mtklein@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1809693002
18 files changed