Revert disable of SDCH on iOS.

Revert disable of SDCH on iOS.

BUG=418975
R=droger@chromium.org

Committed: https://crrev.com/8290aa0050bc527c740ae84e0267f79abc9cb0ce
Cr-Commit-Position: refs/heads/master@{#302879}

[Randy Smith (Not in Mondays), 2014-11-04 19:17:34]

David: Could you review this for me?  I'm looking as much for the process review
as I am for the technical review; my intent is that the disable that I landed
show up in M39, and this re-enable show up in M40 paired with the actual fix for
this problem that was landed in https://codereview.chromium.org/687263002/, and
that the only things that show up in iOS are either the disable (in M39) or the
combination of re-enable and fix (M40).  Do you agree that landing this change
now will satisfy those constraints?

Thanks much in advance.

[droger, 2014-11-04 19:46:55]

Lgtm 
I don't know if this can land on M40 (I think branch point is very close) but in
any case we can probably merge it if it does not make it.

[Randy Smith (Not in Mondays), 2014-11-05 20:04:13]

The CQ bit was checked by rdsmith@chromium.org

[commit-bot: I haz the power, 2014-11-05 20:05:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/699233002/20001

[commit-bot: I haz the power, 2014-11-05 21:54:53]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-11-05 21:56:13]

Patchset 2 (id:??) landed as
https://crrev.com/8290aa0050bc527c740ae84e0267f79abc9cb0ce
Cr-Commit-Position: refs/heads/master@{#302879}