Fix Cardboard FOV

The Cardboard SDK gives Field of View values in Radians, while
WebXR expects them in degrees. Correcting this fixes the "zoomed
in" look of VR sessions.

Bug: 1429100
Change-Id: Ie6709585248dcfa8bbe8147b7e203bd76ba55501
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4567800


Auto-Submit: Brandon Jones <bajones@chromium.org>
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149436}