expose ConvertRadiusToSigma to aid clients in the API transition to sigma

expose ConvertRadiusToSigma to aid clients in the API transition to sigma

NOTRY=True

Committed: http://code.google.com/p/skia/source/detail?r=14501

[f(malita), 2014-05-01 15:05:22]

LGTM

I was about to do the same, as I just ran into this problem when trying to clean
up deprecated Skia calls in Blink :)

[robertphillips, 2014-05-01 15:06:46]

lgtm

[reed1, 2014-05-01 15:07:52]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2014-05-01 15:08:06]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/reed@google.com/264923002/1

[reed1, 2014-05-01 15:08:17]

I'm hacking on a chrome CL that will use this. Will share soon...

[commit-bot: I haz the power, 2014-05-01 15:18:34]

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

[commit-bot: I haz the power, 2014-05-01 15:18:35]

Retried try job too often on Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Nexus7-Trybot
for step(s) BuildBench, BuildEverything, BuildGm, BuildSkiaLib, BuildTests,
BuildTools
http://skia-tree-status.appspot.com/redirect/compile-buildbots/buildstatus?bu...

[reed1, 2014-05-01 15:24:30]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2014-05-01 15:24:50]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/reed@google.com/264923002/1

[commit-bot: I haz the power, 2014-05-01 15:24:57]

Change committed as 14501

[reed1, 2014-05-01 15:25:02]

eric, what is up with the CQ message?

[borenet, 2014-05-01 15:32:06]

On 2014/05/01 15:25:02, reed1 wrote:
> eric, what is up with the CQ message?

Ravi is composing an email to the group, but it's a problem with the new CQ bot.
 I'm going to remove it for now.