Looks like it was committed to Chromium today https://codereview.chromium.org/566083003/ as per this spec http://www.w3.org/TR/SRI/
ni:///
why 3 slashes? any clue?
ni:
//
<empty field>
/
file:: URIs can have it, too (http://superuser.com/questions/352133/what-is-the-reason-tha...)