It doesn't happen in the VM, which has Firefox 41. So I might try reverting to that version next...
Another symptom is that things hang a lot. Even dnf will hang midstream downloading either a package or metadata. No error, no fail, no recovery, just indefinite stall. If I cancel it and just issue the same command, it always completes. And yet non-google sites load find in Firefox. So I can't tell if the dnf stall is related to the Firefox+google services stall.
Chris Murphy