Round XR Bounds Geometry to the nearest CM

The WebXR spec suggests quantizing the stage bounds to the nearest 5 cm.
This provides a first step by quantizing the stage bounds to the nearest
cm.

Bug: 986991
Change-Id: I6c264957c5a25eb2b00fd07e31e7e6f90343c4f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1933200
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718841}
2 files changed