Add nanobench stats scripts to Skia repo.

Add nanobench stats scripts to Skia repo.

These are the scripts I've been homegrowing for measuring perf impact.  I think we found them useful today as a way of sifting through the noise.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/7ba39cb9a6c97f07eb392a1cf99ce65c1f23ded0

[mtklein_C, 2014-11-04 19:48:53]

mtklein@chromium.org changed reviewers:
+ reed@google.com

[danakj, 2014-11-04 19:52:12]

danakj@chromium.org changed reviewers:
+ danakj@chromium.org

[danakj, 2014-11-04 19:52:13]

+1. Adding them to the skia docs site would be +100 :)

[danakj, 2014-11-04 19:52:20]

danakj@chromium.org changed reviewers:
- danakj@chromium.org

[mtklein, 2014-11-21 16:23:53]

mtklein@google.com changed reviewers:
+ tomhudson@google.com
- reed@google.com

[mtklein, 2014-11-21 16:23:59]

mtklein@google.com changed reviewers:
+ mtklein@google.com

[mtklein, 2014-11-21 16:24:00]

PTAL

[Tom Hudson, 2014-11-21 18:51:32]

tomhudson@chromium.org changed reviewers:
+ tomhudson@chromium.org

[Tom Hudson, 2014-11-21 18:51:32]

Document your calling conventions / environment variables and your concerns
about over-interpretation and they'll be good to go IMHO.

[mtklein, 2014-11-24 20:28:54]

The CQ bit was checked by mtklein@google.com

[mtklein, 2014-11-24 20:28:55]

lgtm

[commit-bot: I haz the power, 2014-11-24 20:29:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/703713002/20001

[commit-bot: I haz the power, 2014-11-24 20:40:05]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/7ba39cb9a6c97f07eb392a1cf99ce65c1f23ded0