Revert of Sets the default background color of inline signin and user manager to grey

Revert of Sets the default background color of inline signin and user manager to grey (patchset #8 id:450001 of https://codereview.chromium.org/637083002/)

Reason for revert:
Broke content_unittests on Blink waterfall. See https://code.google.com/p/chromium/issues/detail?id=368225#c5 .

Original issue's description:
> Sets the default background color of inline signin and user manager to grey
>
> The purpose is to avoid the white flash before the web content is loaded.
>
> This CL only handles the view implementation, mac implementation will be handled in the next cl.
>
> BUG=368225
>
> Committed: https://crrev.com/fe517ffc1a9550ff4557b5718b01b103bd134616
> Cr-Commit-Position: refs/heads/master@{#299594}

TBR=rogerta@chromium.org,noms@chromium.org,sky@chromium.org,asvitkine@chromium.org,ccameron@google.com,sievers@chromium.org,ccameron@chromium.org,benwells@chromium.org,fsamuel@chromium.org,nasko@chromium.org,guohui@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=368225
Committed: https://crrev.com/e4c95aeb6a7360f2e915efd20cc6d9c021a23ab9
Cr-Commit-Position: refs/heads/master@{#299624}

[Ken Russell (switch to Gerrit), 2014-10-15 01:51:20]

Created Revert of Sets the default background color of inline signin and user
manager to grey

[commit-bot: I haz the power, 2014-10-15 01:52:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/654123004/1

[commit-bot: I haz the power, 2014-10-15 01:53:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-15 01:55:49]

Patchset 1 (id:??) landed as
https://crrev.com/e4c95aeb6a7360f2e915efd20cc6d9c021a23ab9
Cr-Commit-Position: refs/heads/master@{#299624}