UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:59.0) Gecko/20100101 Firefox/59.0
Platform: Chrome OS

Steps to reproduce the problem:
We have an issue with two of our Chromebook applications on the Chrome 66 beta release.

The application is using Webgl and is made for chromebooks and many schools/students is using it. The applications can not finish loading on Chrome 66, both extensions are working on Chrome 65 and previous versions.

It is repeatable in Chrome 66 on both windows, mac and chromebook.
The Chrome extension can be seen here (the build here only allows launching on Chromebooks. We can send you a modified build if you need builds for other platforms)
https://chrome.google.com/webstore/detail/wedo-20-lego%C2%AE-education/pflionopdgpjckjkafnlamfmonjhccdh?hl=en

We have tracked the issue to being caused by our splash screen.
The splash screen in our application is a fairly standard div element with an image and a progress bar – the div ‘covers’ the webview element containing the webgl code.

Our application is fairly large and can take some time to load, so we need to be able to run both the progress bar splash screen and to be able to initialize the webgl webview in the background. This approach has been working fine in Chrome up to and including Chrome 65, but is not working for us in Chrome 66.

As far as we can tell, the problem for our application in Chrome 66 is, that apparently some DOM optimizations have been added in 66 compared to Chrome 65.
In 66 when the element is not visible it is not given any resources – and then the Unity webgl does not complete loading.

We have identified that we can work around this optimization by moving the splash screen in the DOM so it does not completely hide the webview – if a single pixel of the webview is visible it is enough for it to get resources and the application can finish loading the webgl in the background while animating the splash screen and progress bar in the foreground.

Can you please advise if there is a better/more correct way of allowing the webview to get resources even if it is running in the background – and maybe point us to a resource describing how this can be done?

What is the expected behavior?

What went wrong?
Please see above description. 

Did this work before? Yes Chrome 65.

Chrome version: 66.0.3359.79  Channel: beta
OS Version: 66.0.3359.79
Flash Version: Shockwave Flash 29.0 r0