GitLab

Removes plane detection state, world tracking state and world
information since the general approach of the APIs that we are adding
seems to just add additional entries to XRFrame / XRSession directly,
w/o the layer of indirection. The spec also contains a mechanism of
detecting whether a feature has been enabled through integration with
permissions API - this makes the tracking states unnecessary, since
they were only needed to communicate exactly that.

Change-Id: I36298b05019f87f0de47c992fc29fef987e6e192
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2540575
Commit-Queue: Piotr Bialecki <bialpio@chromium.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832015}