This extension removes "Like Gating" from a Facebook Tab.
Like Gating is when a Facebook tab makes you Like the page before being able to see the real content.
Upon detecting a tab employing this technique, GateKeeper automatically removes the Like Gate and shows the real content. The GateKeeper icon (a Facebook "Like" thumb) will appear in the URL bar to notify you when this has been done.
Clicking the icon allows you to toggle between the two Like states.
This extension is also useful for Facebook developers who need to easily see and test both Like states.
You can install the extension at the offical Google Extension site.