Create dummy engine surface with correct background color until we get a onFirstContentfulPaint

[ekager]

Currently opening a new page temporarily shows a pure white page before loading actual content regardless of the browser theme.

See Fenix issue: mozilla-mobile/fenix#6313

We can use CompositorController clearColor https://mozilla.github.io/geckoview/javadoc/mozilla-central/org/mozilla/geckoview/CompositorController.html
mozilla-mobile/fenix#6313

After talking to the GV team, unfortunately the above solution likely does not work anymore with WebRender enabled. FxR uses a dummy surface with the correct color until they get a onFirstContentfulPaint and that's probably the direction we'd have to go as well to fix this.

┆Issue is synchronized with this Jira Task

[ekager]

I filed this in AC because this is where the onFirstContentfulPaint callbacks live and I figure at the minimum we would need to expose those to Fenix in order to show/hide some dummy background view.

[pocmo]

at the minimum we would need to expose those to Fenix in order to show/hide some dummy background view.

Would it also be an option to hide the geckoview until we get onFirstContentfulPaint() and just show the window background in the meantime?

[ekager]

That sounds way less complicated if that works 🙂

[pocmo]

That sounds way less complicated if that works 🙂

I saw your PR and wonder if you tried this and if that works? If so then we could consider maybe adding this to GeckoEngineView. It already registers an EngineSession.Observer and could use that to hide/show the internal GeckoView. With that we wouldn't need to add anything to Session(State) and the app wouldn't need to do anything manually. :)