mac: Fix an error in a unit_test from linking against the 10.10 SDK.

mac: Fix an error in a unit_test from linking against the 10.10 SDK.

When an application is linked against an OSX 10.9+ SDK, a blit will fail if the
source and destination color formats do not match.

BUG=484203
Committed: https://crrev.com/e5cc32ead01f46e914d0f8b090032fc28de75438
Cr-Commit-Position: refs/heads/master@{#329242}

[erikchen, 2015-05-11 18:12:14]

erikchen@chromium.org changed reviewers:
+ zmo@chromium.org

[erikchen, 2015-05-11 18:12:15]

zmo: Please review.

[Zhenyao Mo, 2015-05-11 19:37:10]

LGTM
Thanks for your persistence on getting to the bottom of this bug.

[erikchen, 2015-05-11 19:40:54]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2015-05-11 19:40:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133163003/1

[commit-bot: I haz the power, 2015-05-11 19:49:26]

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

[commit-bot: I haz the power, 2015-05-11 19:49:27]

Try jobs failed on following builders:
  linux_chromium_gn_dbg on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_gn_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[erikchen, 2015-05-11 21:21:24]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2015-05-11 21:23:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133163003/1

[commit-bot: I haz the power, 2015-05-11 21:51:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-11 21:52:03]

Patchset 1 (id:??) landed as
https://crrev.com/e5cc32ead01f46e914d0f8b090032fc28de75438
Cr-Commit-Position: refs/heads/master@{#329242}