webRequest details object is missing properties to detect the top-level document URL

[lenacohen]

The webRequest details object that is passed to webRequest event callbacks is missing frameAncestors, and documentUrl.

On Firefox, Privacy Badger uses documentUrl and frameAncestors to get the top-level document URL for a given request. On Chrome, we use initiator, but it lacks path information and is not useful for resources belonging to sub frames.

PB can function without initiator or documentUrl/frameAncestors, but we will mis-attribute requests in various corner cases.

Tested on Safari Technology Preview Release 215.