PSA for Chromium / Dawn WebGPU API updates 2021-04-07

Hey all,

*TL;DR:* Lots of breaking changes to catch up to the spec. Some new
features (like create pipeline async). Lots of behind-the-scenes
improvements towards an Origin Trial.

You can find the details of the updates in this document
<https://hackmd.io/BtRPZXulQICjbcZi4tLCdg?view>. Below is the introduction
of it for context.

Chromium’s WebGPU implementation and Dawn’s API try to closely follow
changes to the WebGPU specification. When the WebGPU IDL changes, as best
as possible Chromium and Dawn will support both the “old” and the “new”
version of the IDL at the same time so prototypes can be updated. In JS,
uses of the “old” path will result in a console warning, while when using
Dawn directly, the “old” path will print a warning to stderr.

Note that all changes to Dawn’s API make it closer to webgpu.h that we hope
will allow applications to target both Dawn, and wgpu in native before
being compiled in WASM.

A couple weeks after an update like this one, the “old” version will be
removed. This means that the “old” version of the items below will start
being removed from Chromium/Dawn starting on 2021-04-21.

Cheers,

Corentin