[Bug]: webview tag background color do not follow browser window when reload webview

[PerfectPan]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug report that matches the one I want to file, without success.

Electron Version

21.2.0

What operating system are you using?

macOS

Operating System Version

macOS Big Sur 11.4

What arch are you using?

x64

Last Known Working Electron version

11.4.5

Expected Behavior

Recently, we upgraded our electron version from 11.4.5 to 21.2.0 and met a problem.
The final problem I located is that webview's background color do not follow browser window when reload webview. So it caused from white -> red instead of browser windows' bg color -> red in my demo.

Actual Behavior

Testcase Gist URL

https://gist.github.com/PerfectPan/100900b7758293b8f72b23d0babdb1cc

Additional Information

In our situation, we use webview to load chrome devtools frontend. This app styles background color asynchronous, so we met this problem. A hack way maybe we modify the inspect.html to hardcode our background color in it. But we want to know if there are any other way to solve this.

[dsanders11]

It looks like this first repros in 16.2.8, due to #33546.

cc @codebytere