Perhaps through a search engine of some kind. One with a harmless-sounding name. Maybe "Dragonfly" would be a good name.
In this case, if Google ever does return to China I doubt the authorities would find it more useful for such purposes than existing sources such as iCloud, Bing, and Baidu already are.
If we want to actually make a difference, we might consider calling for those existing services to change their ways. Harder to pressure the domestic Chinese companies, of course, but it's surprising how little attention is paid to Western companies who are actually in China and benefitting from it.
> identify involuntary donors
err... dissidents. Highest political crime - being a 100%-match for a Central Committee member who needs liver transplant.
Better off looking like an alcoholic on paper.
I'm sure we can all be happy if, with the help of Google, China becomes a more harmonious society, without any pesky troublemakers, and that hard-working Chinese Communist Party officials get the transplants they so deserve.