Rename XR supportsSessionMode to supportsSession

Bug: 955033
Change-Id: Ie98cfd7954be59189789d0bbcda73f3fdbe63f3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1577676
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653783}
16 files changed