[Win,Linux] New avatar menu: Don't show the "Sign in to Chrome" button if sign-in is not allowed.

New avatar menu: Don't show the "Sign in to Chrome" button if sign-in is not allowed.
If the SigninManager won't allow signing in, then showing the button makes no sense. The hotdog menu does much the same thing (https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ui/toolbar/wrench_menu_model.cc&l=583)

Mac implementation to follow.

BUG=372812, 310640
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272019

[Marc Treib, 2014-05-20 11:10:01]

PTAL, or feel free to reassign if you're not the right person to review this.
Thanks!

[msw, 2014-05-20 17:16:28]

The profile chooser view isn't shown at all on CrOS, right? If so, LGTM.

[Marc Treib, 2014-05-21 07:36:27]

On 2014/05/20 17:16:28, msw wrote:
> The profile chooser view isn't shown at all on CrOS, right? If so, LGTM.

Right, this is desktop-only so far.
What would CrOS change with regards to this CL?

[Marc Treib, 2014-05-21 07:36:35]

The CQ bit was checked by treib@chromium.org

[commit-bot: I haz the power, 2014-05-21 07:38:26]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/treib@chromium.org/291843002/40001

[commit-bot: I haz the power, 2014-05-21 23:41:35]

Change committed as 272019