guidou@ can you help with triage?

It looks like the issue is that both cameras cannot be open at the same time on Android, at least on some devices.

I can reproduce the issue with https://jsfiddle.net/guidou/8e1cLn1j/ if I set CLOSE_FIRST to false (don't close the track from the first getUserMedia call).
It works fine if I set it to true.

cgfarmer4: do you get the same behavior with this script?
chfremer@: do you know if this behavior is intended due to a limitation in Android?

re #2: Agreed that it seems that not all devices allow opening both cameras simultaneously, see [1].

I am not aware of any Chromium-side code that would restrict to a single camera on Android. Adding mcasas@ in case I overlooked something.

https://stackoverflow.com/questions/30377081/access-both-back-and-front-cameras-simultaneously

I will be away from my Pixel XL for a couple weeks but your example shows using facingMode as a constraint. I have never got that constraint to work with the Pixel. The only way I was able to get it to work was to call MediaDevices.enumerateDevices() and then pass the deviceId as the optional constraint. This might be a different bug altogether.

With that said, your point about both cameras being open seems to be the case in my code as I was not calling stop on the previous mediaStream of the other camera. Just seems odd that it works when you start with the front but not the other way around.

I tested with Samsung Galaxy S8, Nexus 4, Nexus 5x, Pixel and Motorola X Force.

Only the Nexus 5X supports opening both cameras and it works as intended.
All the others fail to open the second camera if the first one is still open.

This looks like it works as intended.

Wrt to the facingMode constraint, it worked on all devices except the Pixel.
Filed  bug 750701  to track the problem with the facingMode constraint on the Pixel.

Closing this bug as WontFix since it's working as intended.

Thanks!