Sketch SkFunction

Sketch SkFunction

Let's start with baby steps in case some bot can't handle this.
I have left many TODOs, most of which I know how to do if this
looks feasible and useful.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/4a9426f0fa812c0f1bffa84f0dae0926607a9543

[mtklein_C, 2015-03-31 19:15:33]

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

[mtklein, 2015-03-31 19:19:05]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-03-31 19:19:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1049223003/1

[commit-bot: I haz the power, 2015-03-31 19:19:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-31 19:19:38]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer,
_not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[mtklein, 2015-03-31 19:29:42]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-03-31 19:30:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1049223003/1

[commit-bot: I haz the power, 2015-03-31 19:38:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-31 19:38:38]

This issue passed the CQ dry run.

[mtklein, 2015-03-31 20:35:32]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-03-31 20:36:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1049223003/20001

[commit-bot: I haz the power, 2015-03-31 20:56:46]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-31 20:56:49]

This issue passed the CQ dry run.

[bungeman-skia, 2015-03-31 21:18:49]

lgtm

[mtklein, 2015-03-31 21:23:41]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-03-31 21:24:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1049223003/20001

[commit-bot: I haz the power, 2015-03-31 21:24:32]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/4a9426f0fa812c0f1bffa84f0dae0926607a9543