Revert "Unified: Hide inactive top buttons instead of dim."

This reverts commit f82109c5b3122d5f88a654e3ba3e5b128e59e48c.

Reason for revert: Crash https://crbug.com/865198

Original change's description:
> Unified: Hide inactive top buttons instead of dim.
>
> On the login screen, we made the settings button and the lock button
> look dim.
>
> According to UX, we should just make them invisible.
>
> TEST=manual
> BUG=864233
>
> Change-Id: I90fc6853b2735a73d426dbb05b2f693be7ff2ce6
> Reviewed-on: https://chromium-review.googlesource.com/1139847
> Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
> Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#575970}

TBR=yoshiki@chromium.org,tetsui@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 864233,865198
Change-Id: I4f3d30c529a5ecc5e68c69cb833bfd6a4c8e2c6d
Reviewed-on: https://chromium-review.googlesource.com/1144860
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576800}
2 files changed