If you check out the listing for Google Wifi, you'll see that it doesn't say much about the power adapter—just that there is one. According to Google's USB Type-C Tsar, Benson Leung, it's actually a Type-C power adapter very similar to the one that comes with the Pixel C. Neat.

The adapter is 15W and rated for 5V 3A, but the router only pulls 9W. You'll be able to use a Pixel C adapter to power Google Wifi, or use your Wifi adapter to power a USB type-C device like the Pixel C or Pixel phones.

Google has so far released phones and Chromebooks that support USB Type-C as the power source. Google Wifi is the first home device to use it. Most similar devices use either DC plugs or microUSB (if you're lucky). It would be nice to see more device makers adopt Type-C power. If we have to get new cables for everything, it might as well be the same one.