It might be actively cooled... though it's really a question if it needs to be in handheld mode.
Pixel C has 20nm X1 inside of it, with max clock of 850MHz (that's 435GFLOPs for those who care) and it's just a regular 7mm thick tablet.
If NS has 14nm X2 (or whatever it's called) SoC inside, given that it's 14-15mm thick and has those air vents, it's possible it might not even need active cooling while handheld.







