[rAC, OSX] Enable final interstitial animation

BUG=286536
R=estade@chromium.org

Review URL: https://codereview.chromium.org/25607011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227830 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227830