Enable strict virtual annotation checks for Mac.

Enable strict virtual annotation checks for Mac.

BUG=417463
Committed: https://crrev.com/3e6c4cf39b9c06c2b23b7e301b1f197902f1cc2d
Cr-Commit-Position: refs/heads/master@{#311365}

[dcheng, 2015-01-13 21:57:18]

dcheng@chromium.org changed reviewers:
+ thakis@chromium.org

[Nico, 2015-01-13 21:58:42]

lgtm \o/

[dcheng, 2015-01-13 21:59:11]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-13 21:59:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/848973002/1

[commit-bot: I haz the power, 2015-01-13 22:55:36]

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

[commit-bot: I haz the power, 2015-01-13 22:55:37]

Try jobs failed on following builders:
  ios_dbg_simulator on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)

[dcheng, 2015-01-13 22:58:58]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-01-13 23:00:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/848973002/1

[commit-bot: I haz the power, 2015-01-14 00:04:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-14 00:05:36]

Patchset 1 (id:??) landed as
https://crrev.com/3e6c4cf39b9c06c2b23b7e301b1f197902f1cc2d
Cr-Commit-Position: refs/heads/master@{#311365}