How does Chrome know my geolocation?

Question

Chrome seems to be very accurate in detecting my location. How does it do it? Can you point me to the source code?

Answer 1

a browser on a pc does not have a gps, however it has an external ip address (usually the router's external ip address). if other components behind the same router has a gps - this pins location to that ip address and via location services attaches this location to the browser.