By the time Chrome was released, Google was already a behemoth. I can’t think of another .com that was anywhere near their size. Microsoft was only 2x bigger by market cap. They were hardly a small company that Microsoft could push around and had the advantage of not being dependent on anything MS was doing.
Google toolbar came first. Slipped in a Google search box on everyone's browser in exchange for blocking Google's competitors' popup ads (Google didn't use popup ads).
Now Google does invasive popovers within the page, etc., and this time with them in charge of the browser they are ahout to implement a plan to block extension makers from stopping it well.
