function markForRemoval(id, mark) {
        if (mark) {
            _idsToRemove[id] = true;
        } else {
            delete _idsToRemove[id];
        }
        exports.trigger("statusChange", id);
    }
Marks an extension for later removal, or unmarks an extension previously marked.
@param {string} id The id of the extension to mark for removal.
@param {boolean} mark Whether to mark or unmark it.