WebXR Device API call agenda, Apr 17th 2018

Apologies for the late agenda.

*Call Agenda Items:*

   - Convert XRFrameOfReference to XRCoordinateSystem (#340
   <https://github.com/immersive-web/webxr/pull/340>)
   - Renamed pointerOrigin and enum values. Updated ray to use vectors (#342
   <https://github.com/immersive-web/webxr/pull/342>)
   - Related to: Representation of a rays in WebXR (#339
      <https://github.com/immersive-web/webxr/pull/339>)
   - Trying to avoid additional canvas when mirroring (#341
   <https://github.com/immersive-web/webxr/issues/341>)
   - Sample test
   <https://github.com/immersive-web/webxr-test-api/blob/master/sample_test.html>
   in the webxr-test-api repo
   - Deferred Session creation (#256
   <https://github.com/immersive-web/webxr/pull/256>)

Please reply with any additional items you'd like to see addressed.

*Call date:* Tuesday April 17th (and every other Tuesday thereafter)
*Call time:* 1:00 PM PST for one hour

WebEx call details are posted to the internal-webvr@w3.org mailing list,
accessible to any community group member.

--Brandon