Revert "WebXR: Do not provide poses to frames without focus"

This reverts commit 666960b1e56dcb39c6c0d7fb3c596c99998b101b.

Reason for revert: Causing a test bug.  Reverting while I investigate that bug (crbug.com/835047).



Original change's description:
> WebXR: Do not provide poses to frames without focus
>
> This change plumbs through focus (both blink/frame and device) to XRSessions, so we
> only call raf callbacks when focused.
>
> BUG=813230
>
> Change-Id: I0aefdce989f6dd60b4cd0acf1a1477fdb2e845b8
> Reviewed-on: https://chromium-review.googlesource.com/1011288
> Reviewed-by: Brandon Jones <bajones@chromium.org>
> Reviewed-by: David Dorwin <ddorwin@chromium.org>
> Commit-Queue: Bill Orr <billorr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#551842}

TBR=ddorwin@chromium.org,bajones@chromium.org,billorr@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 813230
Change-Id: I5c1e1dcb9aaef3fe46c085d6572cea81673e4789
Reviewed-on: https://chromium-review.googlesource.com/1020800
Commit-Queue: Bill Orr <billorr@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552268}
8 files changed