Show 'Brave Browser' as the origin if origin is null
Show 'Brave Browser' as the origin if origin is null

in the permission notification bar

fix #4198

Test Plan:
1. go to brave.com
2. scroll down to the contact section
4. right click on one of the email addresses to open in a new tab
5. the notification bar should say, 'Allow Brave Browser to open an external application?'

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