That would be foolish. Firefox is the only major browser not controlled by one of Google's major competitors. Even without a deal for the search engine default

That would be foolish. Firefox is the only major browser not controlled by one of Google's major competitors. Even without a deal for the search engine default, there are all sorts of reasons that is valuable to Google (collaboration on web standards, an insurance policy for browser design mistakes, not all Firefox users would switch to Chrome and so on).