The Apple 15" MacBook Pro (Late 2016) allows support of third party USB Power Delivery chargers like the Google Universal Type-C Charger 60W.
Using the software from Granite River Labs, we'll look more close at the USB Power Delivery Protocol transactions between the Mac and this charger.
The Google Universal Type-C Charger 60W is shown to declare power profiles of 15 watts (5 volts @ 3 amps), 36 watts (12 volts @ 3 amps) and 60 watts (20 volts @ 3 amps).
The Apple 15" MacBook Pro (Late 2016) then requests 20 volts @ 3 amps from the Google Universal Type-C Charger 60W.
Here the Apple 15" MacBook Pro (Late 2016) displays Sink behavior with supported power profiles of FS (Fixed Voltage & Current) 15 watts (5 volts @ 3 amps), VS (Variable Voltage & Fixed Current) (4.75 - 21) volts @ 4.5 amps and Constant Power of 90 watts.
To further verify the actual power delivered by the Google Universal Type-C Charger 60W, we use an oscilloscope and finds that the charger provides 20 volts @ 0.7 amp to the Mac when well charged.
This indicates that a non-Apple USB Power Delivery based charging source like the Google Universal Type-C Charger 60W can charge the Apple 15" MacBook Pro (Late 2016) but not as fast as the Mac's own Apple 87W USB-C Power Adapter.