1452705 - require DETH objects to bind to a global

Status: NEW

(Core :: DOM: Core & HTML, enhancement, P3)

Description

[Ben Kelly [:bkelly, not reviewing]]

Bug 1450271 is an example where a DETH subclass leaks because it was never bound to a global and therefore did not receive DisconnectFromOwner().  We should consider changing the API so that we can assert that DETH objects are bound to a global.

Comment 1

[Boris Zbarsky [:bzbarsky]]

So right now there are two consumers of the no-arg DETH constructor:

1)  Notification.  This actually binds ... but only on mainthread.  This has a long comment explaining why it needs to be mainthread-only, but that comment seems pretty fishy given that we have other event targets that do bind on non-mainthread.  Certainly the atom bits it's talking about will become irrelevant after bug 1450167, even if they're relevant now (which I don't think they are).

2)  MediaTrack.  Right now we add the track, then Init() it in MediaTrackList::AddTrack.  However, every single place that constructs the MediaTrack has the right owner already, so we could just stop doing this.

Comment 2

[Ben Kelly [:bkelly, not reviewing]]

Note, in bug 1457867 it appears we are running into problems binding every MediaQueryList to the global.  That crash is a 2GB+ OOM trying to expand the nsIGlobalObject::mEventTargetObjects hash table.  I'm changing MediaQueryList to dynamically bind on first event listener add for now.  Long term we might need a better solution, though.  Particularly if we want to do this bug.