Chipworks discovered a ToF proximity sensor, apparently made by ST, next to the front camera in iPhone 7:
"...when we looked at the selfie camera side and took out the sub-assembly, both the ambient light sensor and the LED/sensor module were different from those in the 6s model.
When we took them off and looked at the module, it looked very STMicroelectronics-ish to us. Looking at the die, it is not the same, but definitely similar in style and die numbering (S2L012AC) to the VL53L0/S3L012BA die with the two SPAD arrays, however this time the LED is bonded on top of the ToF die to give a very compact module.
Based on this we think it is safe to conclude that the proximity sensor is now a ToF sensor that can also act as an accurate rangefinder for the selfie camera. It was also in the 7 Plus, so a good design win for STMicroelectronics. So far nothing has been announced by either Apple or STMicroelectronics, but it is yet another one of the subtle improvements that we see in the evolution of mobile phones."