It comes down to who's in charge, and what their motivations are.
Google's motivations include learning everything about you, and how to serve you more ads.
Linus' motivations include writing solid code and flipping people the bird.
It's not just about the current situation, either.
When Linus finally goes to the bitbucket in the sky, there are so many companies, organizations and private individuals with an incentive to keep Linux operating and free from backdoors, we can somewhat rest easy at night.
But with Chromium/Chrome - there are only a handful of organizations in the world that can keep up with the rate of patches coming out of Google. Google de-facto controls the direction of Chromium.
I'm not saying that's worse than the alternative. Maintaining something like that is a hell of a lot of work. Unfortunately, things have become so complex and monolithic that there are only a handful of viable browsers.
At least two of them have source available, so we can start over if we absolutely have to.