Changing options page so it is in the center, has less padding, a drop shadow and a border.

BUG=chromium-os:5956
TEST=none
Review URL: http://codereview.chromium.org/3146030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57068 0039d316-1c4b-4281-b951-d872f2087c98