FAA rules require remote control aircraft operators to get permission from the airfield operator if within 3 miles of the airfield. Google could ask permission from themselves.
Google may still require FAA authorization for the drone flights as the FAA might not consider them "model aircraft"
Moffet airspace is congested for everyday drone operations. It practically shares class D airspace with Palo Alto airport and there is class C airspace for San Jose International right above it.