We don't fully know that.
We know it was forced onto browsers in a manner which reeks of spyware.
We know it was forced onto browsers in a manner which reeks of spyware.
I believe it did technically run enough code to decide whether or not it was enabled, and I'm not sure whether or not its installation was avoidable (I believe enabling SHIELD studies is opt-in [perhaps part of opting in to analytics?]).