First part of new install dialog on Windows. Later changes will

      add tooltips and implementations on other platforms.

BUG=29633

Review URL: http://codereview.chromium.org/1299002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@42639 0039d316-1c4b-4281-b951-d872f2087c98