UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36

Steps to reproduce the problem:
1. Install this extension https://chrome.google.com/webstore/detail/sound-enhancement/jnfbbgcbjbmndefaeopjlicndkpoiijj (or other extension that use tapCapture.
2. Open a video on YouTube.
3. Click on extension icon, click on "Enable". The tab (with Youtube video) switch to "sharing mode".
4. Click on fullscreen button of YouTube video. The video won't be fullscreen, it only fit to browser windows (full inside browser, not inside screen). See attached picture.

What is the expected behavior?
Fullscreen mode need to work in sharing mode of Tab. The sharing mode is the mode that use tabCapture.

chrome.tabCapture.capture({audio:true},function(t){
....
});
chrome.tabCapture.capture({video:true},function(t){
....
});

What went wrong?
Fullscreen cannot work correctly with tabCapture.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 66.0.3359.117  Channel: stable
OS Version: 10.0
Flash Version: 

I am not sure this is a bug or security limitation.
 

Deleted: tabCapture.PNG 1.4 MB

	tabCapture.PNG 1.4 MB View Download