Split SkTRacy into SkTRacy and SkTRacyReffable.

Looks like TSAN can't always suppress our existing implementation of SkTRacy
(what is turning here into SkTRacyReffable).  To minimize flakiness, use
SkTRacy where possible and SkTRacyReffable where necessary.

BUG=skia:
R=robertphillips@google.com, mtklein@google.com, reed@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/388503002
2 files changed