Record third-party pings (navigator.sendBeacon) as tracking
Fixes a part of #367 and #1808. This catches Google Analytics when it's configured to send pings (more commonly, it drops pixels (#794); pixel detection can be added in a separate PR).
Let's see what other new trackers Privacy Badger will catch if it treats all third-party pings as tracking. Besides Google Analytics, I noticed Clicktale, DoubleVerify and mPulse Beacon (akstat.io).
Sites that I see use GA with pings/the beacon API:
- github.com
- lidl.de (Chrome-only for some reason)
- stackoverflow.com
- superuser.com
- telegraph.co.uk
As this adds a new input to our learning engine, this should help when cookie learning has been curtailed (#1851) for whatever reason.
Beacons are one of three transport methods for Google Analytics.
I'm very curious to see if Badger will catch Google Analytics in its pretrained data set with this PR.