Revert 228086 "rAc: improve loading screen sizing methodology"

Suspect for broken ash_unittests: http://build.chromium.org/p/chromium.win/builders/Win8%20Aura/builds/11043

> rAc: improve loading screen sizing methodology
> 
> Moves more logic into the controller and improves behavior when the Loading... screen is showing due to a user changing the active wallet account (which is only possible with multi login).
> 
> BUG=259543
> 
> Review URL: https://codereview.chromium.org/26341003

TBR=estade@chromium.org

Review URL: https://codereview.chromium.org/26491006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228121 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228121