Revert of Rollback option put behind the flag.

Revert of Rollback option put behind the flag. (https://codereview.chromium.org/267393011/)

Reason for revert:
This seems to have broken ResetFirstAfterBootTest.SuccessOnRollbackRequested on http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%282%29/builds/23801.

Original issue's description:
> Rollback option put behind the flag.
> 
> BUG=368860
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=269753

TBR=nkostylev@chromium.org,merkulova@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=368860
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=269762

[vabr (Chromium), 2014-05-12 10:04:24]

Created Revert of Rollback option put behind the flag.

[commit-bot: I haz the power, 2014-05-12 10:04:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vabr@chromium.org/279203002/1

[commit-bot: I haz the power, 2014-05-12 10:05:21]

Change committed as 269762

[Nikita (slow), 2014-05-12 10:58:46]

CQ committed CL and ignored test failure (will file a bug):

https://codereview.chromium.org/267393011

This bot failed but is still seen green on the CL
http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...

[vabr (Chromium), 2014-05-12 12:44:12]

On 2014/05/12 10:58:46, Nikita Kostylev wrote:
> CQ committed CL and ignored test failure (will file a bug):
> 
> https://codereview.chromium.org/267393011
> 
> This bot failed but is still seen green on the CL
>
http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...

That's interesting. Thanks, Nikita, for digging into it!