The HTC 10 comes with a Qualcomm Quick Charge 3.0 enabled charger but also supports limited USB Power Delivery charging. To prove this, we used an oscilloscope and software from Granite River Labs to capture the USB Power Delivery Protocol transactions going between the HTC 10 and the Google Universal Type-C Charger 60W.
The HTC 10 uses the USB Power Delivery protocol to request 10 Watts (5 Volts @ 2 Amps) from the Google Universal Type-C Charger 60W and supports DisplayPort over USB Type-C. By comparison, the LG G5 can be charged using USB Power Delivery at 15 Watts (5 Volts @ 3 Amps) or 18 Watts (9 Volts @ 2 Amps), and also supports DisplayPort over USB Type-C.
Unlike USB Power Delivery which works over USB Type-C, HTC's Qualcomm Quick Charge 3.0 charger that came with the HTC 10 connects to the HTC over a USB Type-A to USB Type-C cable. The Qualcomm Quick Charge 3.0 charger supports higher power profiles such as 12.5 Watts (5V Volts @ 2.5 Amps), 15.3 Watts (9 Volts @ 1.7 Amps), and 15 Watts (12 Volts @ 1.25 Amps). Interestingly enough, after the HTC 10 battery is brought down to 8% charge, we only measured 13 Watts (6.5 Volts @ 2 Amps) of charging as per the scope screenshot below where scope Channel 2 is the charging voltage and scope Channel 3 is the charging current.