It's Google's operating system. Nobody would buy a Samsung, HTC, or Sony phone without Google's Research and Development.
Smartphone manufacturers are in the smartphone business because of Google. If those manufacturers don't like Google's terms, they're free to go Microsoft's route and build their own OS.
I can make exactly the same point in reverse: "It's the manufacturer's phone. If Google doesn't want to offer its OS on terms that comply with EU competition law, it's free to go the Apple route and simply build all of its own phones. Nobody is forcing Google to do anything."
Google and its smartphone partners are both in the business because of each other. If Google had kept Android closed and limited to its own phones, it would not have become the #1 mobile OS -- we'd be using Palm or Microsoft or Nokia or someone else's product.
Smartphone manufacturers are in the smartphone business because of Google. If those manufacturers don't like Google's terms, they're free to go Microsoft's route and build their own OS.
Nobody is forcing these companies to do anything.