Put close_gif() in an anonymous namespace.

Put close_gif() in an anonymous namespace.

Not a big deal, but matches the intention of it being a file-scoped function
better.  This mirrors a recent google3 change for clients who don't use C++11.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/75de4f827fcc92ec129ba872924f6e81c55aa8f0

[mtklein_C, 2015-01-22 16:12:49]

The CQ bit was checked by mtklein@chromium.org

[mtklein_C, 2015-01-22 16:12:57]

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

[commit-bot: I haz the power, 2015-01-22 16:14:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/865243002/1

[commit-bot: I haz the power, 2015-01-22 16:14:05]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-01-22 22:14 UTC

[scroggo, 2015-01-22 18:32:06]

lgtm

[commit-bot: I haz the power, 2015-01-22 18:32:28]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/75de4f827fcc92ec129ba872924f6e81c55aa8f0