Proposal: Track WebGL, WebGL2 and WebGPU usage

[beaufortfrancois]

To better understand how WebGL, WebGL2, and WebGPU APIs are being used on the web platform, I propose adding the following WebDX features:

• Features matching CanvasRenderingContext::RecordUKMCanvasDrawnToRenderingAPI() in Chromium for HTMLCanvasElement and OffscreenCanvas. This would allow us to identify rendering contexts where content has actually been drawn, covering WebGL, WebGL2, and WebGPU.
• A feature matching kWebGPUQueueSubmit in Chromium to specifically track when GPU compute resources are used, rather than just context creation. This is specific to WebGPU since WebGL and WebGL2 don't have GPU compute.

Additionally, we should consider if similar tracking is needed for getCurrentTexture() in WebGPU contexts to fully capture active usage patterns.

@captainbrosset What do you think?

[ddbeck]

I'm not quite sure how to interpret this feature entry request. Feature entries are (mostly) developer oriented, listing various capabilities of the platform that developers might use to build sites and applications. It's not clear to me that there are any developer-facing distinctions described here—more that there might be a distinction between, for example, a developer accessing some canvas interface versus actually drawing something in a canvas. Do I have that right or am I missing some additional capability that our current features don't make clear?