If I understood Boris's comment in bug 1310318 comment #17, this is something we should do.

I can probably take this next week, provided my understanding above is correct.

Comment on attachment 8833810 [details] Bug 1335890 - Factor out nsContentUtils::SubjectPrincipal version that takes JSContext https://reviewboard.mozilla.org/r/109948/#review111068 ::: dom/base/nsContentUtils.cpp:2818 (Diff revision 1) > // > // So we use a singleton null principal. To avoid it being accidentally > // inherited and becoming a "real" subject or object principal, we do a > // release-mode assert during compartment creation against using this > // principal on an actual global. > if (!compartment) { This is my best guess at what each version of SubjectPrincipal() should do. Because of the big comment wall above, this still returns a NullPrincipal without a compartment, even if it marely calls the other version when the JSContext has a compartment (since it requires one).

Hope this is what you had in mind for a followup Boris?

Comment on attachment 8833810 [details] Bug 1335890 - Factor out nsContentUtils::SubjectPrincipal version that takes JSContext https://reviewboard.mozilla.org/r/109948/#review111184 r=me with the one nit below. Thank you! ::: dom/base/nsContentUtils.cpp:2082 (Diff revision 1) > > // static > bool > nsContentUtils::CallerHasPermission(JSContext* aCx, const nsAString& aPerm) > { > // Chrome gets access by default. So I think we should just make CallerHasPermission call PrincipalHasPermission(SubjectPrincipal(aCx)), and we should add such a PrincipalHasPermission. Then we can also call that from nsContentUtils::IsCutCopyAllowed.

Comment on attachment 8833810 [details] Bug 1335890 - Factor out nsContentUtils::SubjectPrincipal version that takes JSContext https://reviewboard.mozilla.org/r/109948/#review111198 ::: dom/base/nsContentUtils.cpp:2082 (Diff revision 1) > > // static > bool > nsContentUtils::CallerHasPermission(JSContext* aCx, const nsAString& aPerm) > { > // Chrome gets access by default. I meant to do that in the next bug 1312260, where I'll actually need PrincipalHasPermission().

> I meant to do that in the next bug 1312260, where I'll actually need PrincipalHasPermission(). Works for me!

Pushed by ryanvm@gmail.com: https://hg.mozilla.org/integration/autoland/rev/ec252adeb5c3 Factor out nsContentUtils::SubjectPrincipal version that takes JSContext r=bz