GitLab

Changes:
- added one more recording including a tracking loss
- added 3 test cases exercising anchors API
- slightly tweaked XrTestFramework to allow for specifying timeouts
explicitly so that the longest anchor test does not time out

Bug: 992035
Change-Id: Ied3db9b459c72cbc1826d8a9e2e7edec90cbaae4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2314663
Commit-Queue: Piotr Bialecki <bialpio@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792001}