[mintplant]

Tracing back through the code, this is only triggered with a URL by the RemotePages watcher, which notifies when the URL matches one of a whitelist. The only whitelisted URLs currently are about:home, about:newtab, and about:tabcrashed.

https://searchfox.org/mozilla-central/source/toolkit/modules...

https://searchfox.org/mozilla-central/search?q=symbol:%23Rem...