Bug 1084010 - [Usage][Cost Control] Browser icon should not appear in Mo...

...bile App Usage list
I understand this property refers to the list of manifest we will hide and collapse into system. If so, please rename to `specialApps` or something like this (making reference to [bug 1079609](https://bugzilla.mozilla.org/show_bug.cgi?id=1079609)) and add a comment pointing to both bugs.