From this question I learned how Google locates me over BSSIDs.
But how does Google retrieve my WLAN-access-point-BSSID when I use Google's services (maps.google.com for example) in Firefox from a Linux-machine (no Android)?
I'm quite sure that there are/were several Android-devices connected to the same router together with my Linux-system. So I guess that Google simply looks up the dynamic (ext.) IP of our router in their database. Can somebody confirm this?
Or is Google able to obtain the MAC of our router?
No, I am not logged into a Google-account. Cookies are deleted when I close FF. And I definitely disabled location services.