This sounds likely, and I wouldn’t be surprised if google had deals with publishers to send additional data, like your computer’s internal IP via webrtc. Alter

This sounds likely, and I wouldn’t be surprised if google had deals with publishers to send additional data, like your computer’s internal IP via webrtc. Alternatively WaPo could be using WebRTC to pull your internal IP and caching with your external IP along and other data to create a unique identifier.