For GOOGLE3, add deref method to SkRefCnt.

This makes it easier to integrate with Blink code using RefPtr/PassRefPtr without pulling in Chrome's SkUserConfig.h.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1890573003

Review URL: https://codereview.chromium.org/1890573003
1 file changed