We should prototype it to ensure we're speccing the right thing.

Do you have an idea of what work all needs to happen for this?

Roughly:

1. Add p3 to our colorspace enums
2. Implement the API surface proposed here: https://github.com/KhronosGroup/WebGL/pull/3292
3. Support separate OS layer webgl canvases marked as p3
4. Tone map(?) p3 canvases into an otherwise-srgb page/wr-rendertarget

For prototyping, I think we can skip 4 for now, though we should be thinking about what we want to do here. I'm not sure what the HTML spec says (will say?) about this.

So having a P3 canvas only effects how it is interpreted by the outside world? What happens if you do texSubImage(ImageElement)? What colorspace should the image be decoded to?

Defined in https://github.com/KhronosGroup/WebGL/pull/3292, generally we would do conversion between spaces. (We basically do this already for YUV content, so this is sort of part of #1)

Enable (direct) external surface compositing for MacIOSurfaces.
Works on Mac.

Backed out changeset 071aa43a0419 (bug 1703654) for causing build bustages in SharedSurfaceDMABUF.

Backout link: https://hg.mozilla.org/integration/autoland/rev/a4c8cdae300f6ed787c8961ae3d4780772f1d161

Push with failures

Failure log

Oh, hah, of course, platform-specific-compiled code

Backed out for causing bustages on IPCMessageUtils.h

• backout: https://hg.mozilla.org/integration/autoland/rev/e68f370836a2890d23e7962078671574c6b1dea7
• push: https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&selectedTaskRun=TZ0VnLK4R52oBIii-csYKg.0&revision=718ead395698d5aeef7c91210e8408d9570c5582
• failure log: https://treeherder.mozilla.org/logviewer?job_id=376194144&repo=autoland&lineNumber=8912

[task 2022-04-28T21:19:41.524Z] 21:19:41     INFO -  /builds/worker/workspace/obj-build/dist/include/mozilla/dom/WebGLIpdl.h:237:14:   required from here
[task 2022-04-28T21:19:41.525Z] 21:19:41    ERROR -  /builds/worker/workspace/obj-build/dist/include/ipc/IPCMessageUtils.h:66:3: error: static assertion failed: PlainOldDataSerializer can only be used with trivially copyable types!
[task 2022-04-28T21:19:41.525Z] 21:19:41     INFO -     static_assert(
[task 2022-04-28T21:19:41.525Z] 21:19:41     INFO -     ^~~~~~~~~~~~~
[task 2022-04-28T21:19:41.525Z] 21:19:41     INFO -  /builds/worker/workspace/obj-build/dist/include/ipc/IPCMessageUtils.h: In instantiation of 'struct IPC::PlainOldDataSerializer<mozilla::WebGLContextOptions>':
[task 2022-04-28T21:19:41.526Z] 21:19:41     INFO -  /builds/worker/workspace/obj-build/dist/include/mozilla/dom/WebGLIpdl.h:219:8:   required from 'struct IPC::ValidatedPlainOldDataSerializer<mozilla::WebGLContextOptions>'
[task 2022-04-28T21:19:41.526Z] 21:19:41     INFO -  /builds/worker/workspace/obj-build/dist/include/mozilla/dom/WebGLIpdl.h:247:14:   required from here
[task 2022-04-28T21:19:41.526Z] 21:19:41    ERROR -  /builds/worker/workspace/obj-build/dist/include/ipc/IPCMessageUtils.h:66:3: error: static assertion failed: PlainOldDataSerializer can only be used with trivially copyable types!
[task 2022-04-28T21:19:41.527Z] 21:19:41    ERROR -  gmake[4]: *** [/builds/worker/checkouts/gecko/config/rules.mk:659: OffscreenCanvasDisplayHelper.o] Error 1
[task 2022-04-28T21:19:41.527Z] 21:19:41     INFO -  gmake[4]: Leaving directory '/builds/worker/workspace/obj-build/dom/canvas'
[task 2022-04-28T21:19:41.527Z] 21:19:41    ERROR -  gmake[3]: *** [/builds/worker/checkouts/gecko/config/recurse.mk:72: dom/canvas/target-objects] Error 2
[task 2022-04-28T21:19:41.527Z] 21:19:41     INFO -  gmake[3]: *** Waiting for unfinished jobs....

Oookay, Maybe<enum class> isn't trivially copyable on old gcc?

Start moving away from manual (risky!) IsTriviallySerializable<>.

https://hg.mozilla.org/mozilla-central/rev/bd0bcbae38bd
https://hg.mozilla.org/mozilla-central/rev/f2d46bb91c9d

== Change summary for alert #34063 (as of Fri, 06 May 2022 18:45:56 GMT) ==

Improvements:

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=34063