Now that it's no longer in beta, Google Chrome has been added to Google Pack. Firefox bundled with Google Toolbar is still available, but you need to explicitly select it. Adding Chrome to Google Pack means that existing users will be informed about the new software and the new users will install Chrome instead of Firefox.
Google contributed significantly to Firefox's popularity by promoting it on the homepage, including the browser in a software bundle and encouraging publishers to promote Firefox. Google's official alternative to Internet Explorer is now Chrome.