I don't like this name, but that's a very minor concern.

I'm not a fan of this either, but after reading through immersive-web/webxr#999 I at least understand why we need a different name. (Although shouldn't this be extended from XRLayer as defined in the core spec now?)

AS far as naming goes, OpenXR refers to all layers as "XrCompositionLayer_____" so maybe XRCompositionLayer or XRCompositorLayer could work as alternatives here? Other ideas off the top of my head: XRLayerBase (May be kind of confusing since XRLayer is actually the base one.) XRBindingsLayer since they come from and XR____Binding object? Or we could go the Microsoft route and define an XRLayerEx 😆

If we end up keeping XRGenericLayer it's fine, it just sounds slightly awkward to me.

One other option, I guess, is that since the amount of shared values here is limited and there's certain attributes that we're sharing across all but one layer type already, maybe we just skip having this intermediate layer type all together and have each layer copy these into their own interface.

It's not the most elegant thing ever, but there's not a whole lot that this structure concretely buys us anyway besides preventing you from passing an XRWebGLLayer into get[View]SubImage(). But even that will need to make sure that the layer was not created by a different XR____Binding object in it's algorithm anyway (because we don't want WebGL bindings to return images for WebGPU-created layers.) So maybe i wouldn't be a terrible things to drop this type from the hierarchy.

If we end up keeping XRGenericLayer it's fine, it just sounds slightly awkward to me.

I like the name XRCompositionLayer. I will update the PR with that name.

One other option, I guess, is that since the amount of shared values here is limited and there's certain attributes that we're sharing across all but one layer type already, maybe we just skip having this intermediate layer type all together and have each layer copy these into their own interface.

There's still quite a bit of common interface between the composition layers so I think we should keep a common base class.