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

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

I'm going to disable it on Linux entirely instead of restoring the flag.

I'll merge that disable to dev/beta/stable, then write a change that
actually examines nsswitch.conf to see if the hosts config is standard.

BUG=117655
Committed: https://crrev.com/9687e96365b450552b101213185f32fd382d05f0
Cr-Commit-Position: refs/heads/master@{#320310}

[Deprecated (see juliatuttle), 2015-03-10 22:22:45]

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

[Deprecated (see juliatuttle), 2015-03-10 22:22:45]

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

[Deprecated (see juliatuttle), 2015-03-10 22:22:46]

PTAL, davidben.

[davidben, 2015-03-11 00:53:24]

lgtm

[Deprecated (see juliatuttle), 2015-03-12 15:49:44]

The CQ bit was checked by ttuttle@chromium.org

[commit-bot: I haz the power, 2015-03-12 15:50:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/995833003/1

[commit-bot: I haz the power, 2015-03-12 17:33:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-12 17:34:07]

Patchset 1 (id:??) landed as
https://crrev.com/9687e96365b450552b101213185f32fd382d05f0
Cr-Commit-Position: refs/heads/master@{#320310}