Mozilla, the organization behind the popular Firefox browser, is a non-profit organization and that status allows it to run experiments that a for-profit organization couldn't quite justify to its shareholders. It still has to make money, though, and the majority of the organization's income (84%) comes from a revenue-sharing partnership with Google. This cooperation ended in November, though. Given Google's own efforts in the browser market with Chrome, many wondered if Google would opt out of renewing its deal with Mozilla. We don't need to worry about the (financial) future of Firefox anymore, though, as Mozilla just announced that it has renewed its search relationship with Google for at least three additional years.
The exact details of agreement weren't disclosed, but both companies were obviously put into a somewhat awkward position, as Mozilla now had to make a deal with its biggest competitor and Google had to decided on whether it wanted to continue to help the only real competitor to Chrome. In the end, though, Google would have lost a lot of goodwill if it had decided against this deal.
It's not clear if Mozilla was also in talks with Microsoft to make a similar deal that would have made Bing the default search engine on Firefox. The company did release a special edition of its browser with Bing as the default in October, though.