Webview sometimes displays blank on launch, until scroll

[gmackall]

I noticed this while testing flutter/engine#52532 (with the repro sample from #146570) but it occurs on main.

Sometimes (not always), the webview just displays blank on launch. As soon as I scroll it it will display properly.

I write webview because I haven't tested with other platform views, but I suspect this would affect any platform view.

[gmackall]

Looks like it can also sometimes only display half of the webview!

[johnmccutchan]

@matanlurey Once we figure out the root cause of these two rendering issues, this is probably a good candidate for an integration test.

[timbotimbo]

I did some testing today, to see if some fixes for virtual display issues are included in 3.22 stable. (They are)

I had it show up invisible once, on first boot after app install. However another ~20 retries on the same device didn't reproduce it.
(Samsung S20FE Android 13)

This was using flutter_unity_widget, which is basically a just a platform view hosting a SurfaceView.

I did not catch any logs as I immediately tried to reproduce it. Will report back if I see it again and this issue isn't updated any further.