Webcam is not detected

Issue generated from Tuleap's migration script. Originally submitted by: rugk (rugk)

In my case the (built-in-)webcam is not detected.

* Environment:
Fedora 26, GNOME

v1.0

* Reproduce steps:
Go into the settings -> Media.

* Expected result:
Detect and offer webcam.

* Actual result:
The fields for webcams are greyed out in the settings. There is a black "image" on the right side.

BTW Cheesy (preinstalled app under GNOME) does detect my webcam. Same as Firefox with WebRTC.