The case here was just injecting a domain. There's another thread for this post pointing out you would also need to inject a malicious root cert for https traffic, which is correct, but not impossible (and given some bad/lazy practices I've seen places do when they sign their own certs for internal infrastructure, not a far stretch)
If they can do that, they can spoof or proxy any website and collect your passwords, auth cookies, and anything else sent over the network. At that point, who cares if they can also see how much CPU you're using?
So if you can just trick someone into trusting a bogus root CA, take control of their DNS resolution, and get them to open an attacker controlled domain in Chrome then you can... Use this API to get information about their current CPU utilisation.