Revert "Async DNS: Remove toggle from about:flags"

Revert "Async DNS: Remove toggle from about:flags"

This reverts commit eabf1f5baba38d46921acd6edda594f942f7d6a1.

Removing the toggle in about:flags breaks a workaround for users who
have nonstandard nsswitch configurations for hosts.

Revert the removal until we properly check nsswitch.conf before
assuming a standard configuration.

BUG=117655
Committed: https://crrev.com/5f379e0e00068336aec9b4b78a49826b424152da
Cr-Commit-Position: refs/heads/master@{#319725}

[Deprecated (see juliatuttle), 2015-03-09 18:23:15]

ttuttle@chromium.org changed reviewers:
+ davidben@chromium.org

[Deprecated (see juliatuttle), 2015-03-09 18:23:15]

ttuttle@chromium.org changed required reviewers:
+ davidben@chromium.org

[Deprecated (see juliatuttle), 2015-03-09 18:23:16]

PTAL, davidben.

[davidben, 2015-03-09 18:29:07]

lgtm

[Deprecated (see juliatuttle), 2015-03-09 18:48:12]

The CQ bit was checked by ttuttle@chromium.org

[commit-bot: I haz the power, 2015-03-09 18:49:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/987133003/1

[commit-bot: I haz the power, 2015-03-09 20:45:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-09 20:49:43]

Patchset 1 (id:??) landed as
https://crrev.com/5f379e0e00068336aec9b4b78a49826b424152da
Cr-Commit-Position: refs/heads/master@{#319725}