Bug 1043762 - Volume buttons don't do anything in Settings and previewing new ringtones

Why did you remove this? I'm pretty sure that without this, things won't work if you open the ringtones app, hide it (e.g. by switching to another app) and then return to it and try to preview a ringtone.

Of course, you'll need to make sure you can call `_setExclusiveMode(true)` multiple times in a row.