UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36

Steps to reproduce the problem:
Description:
If we have a canvas size that is 300x220 or greater, we are finding that calling captureStream is causing the canvas to not update as expected when things are drawn to it.  Please note the browsers/OS that this occurs on later in this report.

Example JSBin
http://jsbin.com/balekem/edit?html,js,console,output

When this JSBin opens/runs - note that the canvas size is 200x200 (find the comment that says ‘Works with these dimension’).  Every second, you will see the image that is drawn on the canvas change.

Note also that the following line is commented out:
//var stream = canvas.captureStream();

To verify the canvas is ok with larger sizes, change the size to 300x220.  Leave the captureStream line commented out - and it will still work at the larger size.

To break it - using the 300x220 size - uncomment the captureStream line.  Run it and you will see that the canvas no longer updates as expected.

Interesting note: Once broken, if you comment out captureStream again (and still use 300x220) it won’t work.  Refresh the browser with these values - still won’t work.  You have to open a new Chrome tab from another Chrome window (or fully restart Chrome) before this will work again at the 300x220 size.  Once it has broken the existing tab seems to stay broken.  When in the broken state - if you change back to the smaller 200x200 size - it will still work.

We feel this might be related to the following bug but aren’t totally sure:
https://bugs.chromium.org/p/chromium/issues/detail?id=810330

Helpful Note
In the browsers that have issues, if we turn OFF ‘Accelerated 2D canvas’, this appears to work correctly.  Turn it back on, and it breaks again.

What OS/Browser Versions Have This Issue

We have found that this issue occurs on Mac High Sierra with the following Chrome versions:
Version 65.0.3325.181 (Official Build) (64-bit)
Version 66.0.3359.117 (Official Build) beta (64-bit)

On the same Macs, running the following version of Chrome Canary - we find that everything works correctly:
Version 68.0.3398.0 (Official Build) canary (64-bit)

On Windows, we find that this works correctly in Chrome 65.  It appears to only break on the Mac.

What is the expected behavior?
In the scenario described in the 'Steps to reproduce the problem', we expect Chrome 65/66 to behave the way Chrome 68 does - meaning that larger canvas sizes should not prevent canvas updates when captureStream is used.

What went wrong?
In the 'Steps to reproduce the problem', it mentions how to see this bug in action.  The broken state is that when larger canvas sizes are used on a Mac, with Chrome 65/66, the canvas no longer updates.  Using smaller canvas sizes, everything works correctly.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 66.0.3359.117  Channel: n/a
OS Version: OS X 10.13.2
Flash Version: 

I don't have exact versions of when this worked, but this has been a feature in our product that has worked fine until recently.  We feel like something regressed around Chrome 65, but don't know the exact version when this started to fail.