Fix black background in website settings dropdown.

Fix black background in website settings dropdown.

The permission spinner in the website settings popup had a black
background on certain devices. The bug was that the background was a
defined using a <shape> element that didn't have a <solid> element
inside of it (and certain devices default to a black fill color if
<solid> isn't specified).

Rather than fixing the immediate problem, this rewrites the code a bit:
The line under the Spinner is now a View with 1dp height rather than the
background of the Spinner's TextView. As a side-benefit, the underline
now extends all the way to the right edge of the spinner.

BUG=449643
Committed: https://crrev.com/168e275c4b6a6f0eb34cea473474fdeb997f588d
Cr-Commit-Position: refs/heads/master@{#313833}

[newt (away), 2015-01-29 23:22:04]

newt@chromium.org changed reviewers:
+ sashab@chromium.org, tedchoc@chromium.org

[newt (away), 2015-01-29 23:22:05]

PTAL

screenshot on the bug:
https://code.google.com/p/chromium/issues/detail?id=449643#c7

[Ted C, 2015-01-29 23:24:37]

lgtm

[newt (away), 2015-01-29 23:33:01]

The CQ bit was checked by newt@chromium.org

[commit-bot: I haz the power, 2015-01-29 23:34:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/870143003/1

[commit-bot: I haz the power, 2015-01-30 00:19:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-30 00:20:12]

Patchset 1 (id:??) landed as
https://crrev.com/168e275c4b6a6f0eb34cea473474fdeb997f588d
Cr-Commit-Position: refs/heads/master@{#313833}