Steps to reproduce the problem:
1. Go to this link https://addpipe.com/media-recorder-api-demo/ and start recording 
2. While it is recording, open a new tab in Chrome and go to the same link and start recording
3. Stop the recording in the first tab and stop the recording in the second tab.
4. Download resulting videos to see that the recording from the second tab does not contain any data (0 KB file)

What is the expected behavior?
When trying to access the camera and microphone in the second tab, a NotReadableError should be thrown OR recording audio/video in both tabs simultaneously should work as expected and produce valid files.

What went wrong?
The recording made in the second tab does not contain any data. The resulting recording is a 0 KB file.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 71.0.3578.99  Channel: stable
OS Version: 7.0
Flash Version: 

Possible related bug: https://bugs.chromium.org/p/chromium/issues/detail?id=924081