Fixes compile error

Committed: https://crrev.com/2a70090f34ab279ca1e7097568cc7db3e5acd17b
Cr-Commit-Position: refs/heads/master@{#292991}

[scottmg, 2014-09-02 19:44:53]

Yeah, seems like a good idea if there's no build complaining. There's a lot of
_USE_MATH_DEFINES per
https://code.google.com/p/chromium/codesearch#search/&q=_USE_MATH_DEFINES&sq=...

Can you tag with https://code.google.com/p/chromium/issues/detail?id=409940 too?

LGTM

[sky, 2014-09-02 19:47:04]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-09-02 19:54:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/533863002/1

[scottmg, 2014-09-02 20:28:10]

On 2014/09/02 19:54:59, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
>  https://chromium-status.appspot.com/cq/sky@chromium.org/533863002/1

Hey, would you mind just landing this? Lots of things are broken w/o this and I
realize now the CQ doesn't test this config anyway.

[sky, 2014-09-02 20:39:33]

Committed patchset #1 to pending queue manually as ecdbf7a (presubmit
successful).

[commit-bot: I haz the power, 2014-09-10 03:20:34]

Patchset 1 (id:??) landed as
https://crrev.com/2a70090f34ab279ca1e7097568cc7db3e5acd17b
Cr-Commit-Position: refs/heads/master@{#292991}