Re: "limit sharing of user data with third parties"
"Are they just doing the same as they're doing for Chrome, killing off competing advertisers' data streams and keeping it all to themselves?"
Absolutely not! Oh they're definitely doing that, but they're certainly not just doing that. They also get the benefits of a completely new blob of code that nobody knows about. That means that people who try to use Android with Google software on it won't be able to evade their tracking as well as they could and those that try to reimplement Google behavior will have to start over on some bits. That code also hasn't been reviewed by privacy organizations, meaning they can put a delay on privacy action by claiming that their new code respects the users and follows the law (we all know it doesn't). There are probably more evil plans with it as well.
Biting the hand that feeds IT
