Bug 921050 - Send email in the background.

We explicitly request the "audio-channel-notification" permission.  I think it may be a platform bug that the <audio> element in native code requires the app to be visible (or rather !ownerDoc->Hidden) and does not sufficiently check our audio channel permission cascade.

Specifically, I looked into this a while back for clock alarms when :mcav took over and I recall the native code suggesting that the alarm playing shouldn't work at all, but then I found there was the attention screen which allows the clock app to force itself to be visible, and from that context the check would pass.  Quickly skimming http://dxr.mozilla.org/mozilla-central/source/content/html/content/src/HTMLMediaElement.cpp again (search on Hidden()) seems to imply that it may indeed be the case that the platform is naively causing whatever the intent of the audio permissions are to be defeated.

I suggest we log a bug / find an existing bug / send a mail to dev-b2g or dev-gaia.  And by we I mean not me :)  I also suggest maybe we track this as a follow-up since depending on the outcome we may end up using notificationHelper for this or not/etc./etc.