Maybe FOUC is not the right term to define it. Judge yourself.

cabezachumbo@ Thanks for the issue.

Tested this issue on Ubuntu 14.04 and Windows 10 on the reported version 66.0.3359.139, latest Stable 66.0.3359.181 and Canary 68.0.3439.0 and unable to reproduce the issue by following the below steps.

1. Launched Chrome and opened many new tabs.
2. Closed the last active tab and cannot observe any white flash when the focus is moved to the previously active tab.
3. Tried adding a dark theme to Chrome and still no flash is observed.
4. Tried the issue on Chromium build as well and unable to reproduce the issue.
Attached is the screen cast for reference.

Request you to check and confirm if anything is missed from our end in triaging the issue.

Also adding 'TE-NeedsTriageFromHYD' label and requesting Inhouse team to look into this issue, as this issue was reported on Linux Debian and this setup is not available at TE end.

Thanks..

Deleted: 845621.ogv 5.4 MB

	845621.ogv 5.4 MB View Download

I see what OP is talking about.

Deleted: white-flash.mp4 4.4 MB

	white-flash.mp4 4.4 MB View Download

OK, first of at all thank you very much for looking into this issue.

Excuse me for not explaining the problem in detail Susan. You didn't see the white flashes because you loaded the new tab page. It does not happen in the new tab page. Another thing that Susan did is that she actually opened the tab in the foreground. You can't open the tab in the foreground, you just have to load it as a background tab. Don't load it in the foreground.

You can see the actual problem in the video that thereald posted just above using Windows 10 as you can see. Thank you very much for posting it thereald.

If you want to know anything else you can ask.
Regards.

I am remaking the steps to reproduce the problem for further clarity:

Steps to reproduce the problem:
0. Optional. If you want to see the problem very clearly, first load a global dark style CSS with dark backgrounds in the browser.
1. Open many pages in new tabs **in the background**. Don't click on them, let them load in the background. Don't use the newtab page for reproducing the issue.
2. Then, close the actual tab to automatically go to the next tab that was previously loaded, giving sometimes (frequently) a white flash in the process.

Example for reproducing it: Search something in Google. Then, middle-click on many different search results pages to load them in new tabs in the background and let them load in the background. Don't click on them. Finally, close the current tab one by one to see the white flashes.

I made a video on how to reproduce the bug:
https://www.youtube.com/watch?v=pLUGCoG7iis

cabezachumbo@ -- In reply to Comment #6, could you please share the theme used by you to reproduce the issue in Step - 0 (global dark style CSS with dark backgrounds in the browser) in order to reproduce the issue.

Tried using the theme from below URL on Debian Rodete on latest Chrome #66.0.3359.181 and was not able to reproduce the issue.
https://chrome.google.com/webstore/detail/dark-theme-for-google-chr/annfbnbieaamhaimclajlajpijgkdblo?hl=en

As requested, please share the sample them which is being used by you to reproduce the issue. It would help us in reproducing and triaging the issue further.

Thanks!

Thanks for looking into it Pnangunoori.

What I mean in step 0 is a global dark CSS style like this one, that you can use with an extension like Stylus. https://pastebin.mozilla.org/9086278 

The bug is reproducible whether you use a dark CSS style or not. The thing is that using the dark CSS you can perceive it very very clearly.

If you have not, please watch the video that I made on how to reproduce the bug:
https://www.youtube.com/watch?v=pLUGCoG7iis

Thank you very much.
Regards.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

A simple version of the CSS code to see the problem clearly is this:

@-moz-document regexp("https?://(?!(x)).*") {
* {background-color: #222 !important;
       color: #b9a980 !important}
}

Use it with Stylus: https://chrome.google.com/webstore/detail/stylus/clngdbkpkpeebahjckkjfobafhncgmne

Also, I want to make clear that this is reproducible both in Linux and in Windows 10, as thereald showed above.

Another option to see the flashes clearly is using this extension instead of the css rules:
https://chrome.google.com/webstore/detail/dark-reader/eimadpbcbfnmbkopoojfekhnkhdbieeh

Able to reproduce this issue on Win 10, Mac 10.13.4 with chrome Stable #66.0.3359.181, Canary #68.0.3440.6 and also on earlier version M60-60.0.3100 
This is a non-regression issue, hence marking it as untriaged

Attaching the screen-cast for reference.

Note: For M60 used an old extension https://chrome.google.com/webstore/detail/dark-retired/oibheihomapbjogmoabgfbkchjchpdfp

Deleted: 845621-M60.mp4 2.2 MB

	845621-M60.mp4 2.2 MB View Download

That's what I am talking about. Thank you kkaluri. It would be really nice if someone could fix it, it is very annoying. Thanks for the attention everybody!

Was this fixed recently? I am no longer able to reproduce this on macOS 10.13.6 with Chrome Canary 69.0.3497.0. Easily reproducible on the same machine with Chrome Stable 67.0.3396.99.

After some additional investigation, I have figured out that this issue is actually only fixed when #upcoming-ui-features is set to enabled in chrome://flags. At the moment this flag is available in Dev and Canary channels.

**UI mass Triage**

Still able to reproduce the issue on latest versions hence adding appropriate labels.