This actor property defaults to false. If it is set to false, and the preference
dom.jsipc.check_safeForUntrustedWebProcess is set to true, then the actor cannot
be loaded into a web or file process. The idea is that if an actor can be put in
a process that can contain web content, then it is be a potential vector for a
sandbox escape, so you should have to opt-in to that behavior.
In addition to adding some tests for this behavior, this patch also adds the
safeForUntrustedWebProcess property to the test actors TestWindow and
TestProcessActor in dom/ipc/tests/.
The properties are added to actors in earlier patches because the new tests
that flip the pref to true will fail otherwise. In other words, those tests
serve as a basic smoke test for the browser working when the pref is true.
Differential Revision: https://phabricator.services.mozilla.com/D302128
Andrew McCreight
84fc31638e