Your working definition of what an illegal anti-competitive use of monopoly power is seems to be the reverse of what I've heard before. Under your definition,

Your working definition of what an illegal anti-competitive use of monopoly power is seems to be the reverse of what I've heard before. Under your definition, Chrome is supporting the even stronger pre-existing monopoly Google has on search or ads, and therefore is bad. Usually anti-competitive actions are seen as a player using its monopoly to support emergence into a new market, not to build a moat around an existing market they already are dominant in. For example, under your framing, Microsoft's usage of Internet Explorer would have been bad not because it came pre-installed with Windows, but because it was Windows-only (or worked best on Windows) thus supporting the existing Windows monopoly. I don't know if this reasoning can hold legally---merely because I have never seen it used before.