Reland: Timezone auto update option should be available by default.

Reland: Timezone auto update option should be available by default.

This reverts commit 44036d053dc7731deb8fdf5d20603bbb8b1c19a5
From review: https://codereview.chromium.org/899113002

Original issue's description:
> This CL makes "timezone auto update" feature available (but switched off by
> default) to users. And adds flag to disable this feature.
>
> BUG=416494
> TEST=manual
>
> Review URL: https://codereview.chromium.org/898503002

TBR=stevenjb@chromium.org,dpolukhin@chromium.org,isherman@chromium.org
BUG=416494
Committed: https://crrev.com/be310d4ac783dc038b1069c4b2ee1b51408661b4
Cr-Commit-Position: refs/heads/master@{#315056}

[Alexander Alekseev, 2015-02-06 15:46:28]

The CQ bit was checked by alemate@chromium.org

[commit-bot: I haz the power, 2015-02-06 15:47:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/909453002/1

[commit-bot: I haz the power, 2015-02-06 17:29:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-06 17:30:13]

Patchset 1 (id:??) landed as
https://crrev.com/be310d4ac783dc038b1069c4b2ee1b51408661b4
Cr-Commit-Position: refs/heads/master@{#315056}