OK, thanks for the explanation. According to your comment on https://github.com/crosswalk-project/crosswalk/pull/1113/files#diff-d5913b29148ed1eca3175a8c33dd80d6R194 , since currently user action is not involved the permission granting. So the preference is not necessary at least in this PR, right?
It's ok to me, but i prefer to introduce necessary things on right PR to make it easier/clearer to review.