I don't have any internal knowledge, but I would like to point out that it can be more than one thing. There's Chrome, in competition with Firefox, Mozilla's c

I don't have any internal knowledge, but I would like to point out that it can be more than one thing. There's Chrome, in competition with Firefox, Mozilla's core business. There's also Google increasingly looking like a search monopoly, whereas Mozilla's mission is to "promote choice and innovation on the Internet." There's also the fact that Google are now feeling so secure about their grip on search that they were looking to reduce the amount they were paying to Mozilla in their partnership. Individually, perhaps none of the reasons was quite enough for Mozilla to ditch their partnership with Google, but combined, it makes a whole lot of sense.