Make sync/sign-in error notifications actionable on click.

Make sync/sign-in error notifications actionable on click.

Since there is only one button, clicking the notification will perform
the same action as the button per PM/designer decision.

BUG=393680
R=atwilson@chromium.org
TEST=manual

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283438

[Andrew T Wilson (Slow), 2014-07-15 10:03:19]

lgtm

[michaelpg, 2014-07-15 17:48:22]

The CQ bit was checked by michaelpg@chromium.org

[commit-bot: I haz the power, 2014-07-15 17:52:51]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/michaelpg@chromium.org/395463005/1

[commit-bot: I haz the power, 2014-07-16 02:23:43]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-07-16 02:42:42]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-16 02:42:43]

Try jobs failed on following builders:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[michaelpg, 2014-07-16 03:41:04]

The CQ bit was checked by michaelpg@chromium.org

[commit-bot: I haz the power, 2014-07-16 03:43:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/michaelpg@chromium.org/395463005/1

[commit-bot: I haz the power, 2014-07-16 18:21:27]

Change committed as 283438