Using wifi networks around a device is Google's standard, low-power way to determine a device's location. In a cellphone it is used so that you don't have to fire up the power-hungry GPS chip.

Since they built the entire infrastructure and database of wifi access points and locations (by scanning from the streetview vehicles and syncing with GPS) they also use it for the desktop browsers.

Which if you legitimately need the location of a "desktop" (which here includes Laptops) would be a nice way to go. It's just a bit of an unclear situation with regards to consent, especially informed consent.

(this is not to be confused with Chrome's private API chrome.networkingPrivate, which is used by the device owner to be able to pick and configure wifi networks without leaving Chrome)

strings /opt/google/chrome/chrome | grep -i wifi | grep -i loca

../../services/device/geolocation/wifi_data_provider_linux.cc ../../services/device/geolocation/wifi_data_provider.cc ../../services/device/geolocation/wifi_data_provider_common.cc