Reland [skjson] Size-constrained input API

Pass an explicit input size instead of requiring a C string.

Thanks to mtklein's clever trick, this has no measurable perf impact.

TBR=
Change-Id: Ic8cb1dc75f4d0814e5b2c80038d1b8d3a7b072ab
Reviewed-on: https://skia-review.googlesource.com/134946
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
5 files changed