Omnibox: Launch URL Demotion in the Fakebox by Default

This has been approved for launch.

BUG=

Review URL: https://codereview.chromium.org/182313014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255606 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255606