In version 49, the buttons are no longer in the omnibar. They now show up with the browser actions as buttons. They are greyed-out when they can't be used. In addition, every extension now has a button in the browser action area. The hidden buttons are now at the top of the hamburger menu.Here is the Google Groups announcement and discussion of this change: https://groups.google.com/a/chromium.org/d/topic/chromium-extensions/7As9MKhav5E/discussion