Implement WebXR lighting estimation API

This implements the API outlined in the explainer here:
https://github.com/immersive-web/lighting-estimation

Initial components of this implementation were done by bialpio@.

Bug: 1034135
Change-Id: I98ba7d3e7c166c6ac2254efae4f5b79e4bb95f48
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1965850
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Piotr Bialecki <bialpio@chromium.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Will Cassella <cassew@google.com>
Cr-Commit-Position: refs/heads/master@{#732270}
53 files changed