Changes to Chrome's WebVR origin Trial

Hey all!

I and the rest of the WebVR team wanted to let everyone know what's going
on with Chrome's WebVR Origin Trial, as there's some changes coming up.

While we missed the first week of the Chrome 59 beta, the next release of
the Chrome Beta branch will be starting a new WebVR Origin Trial. This
means that even if you had Origin Trial tokens for WebVR before you'll have
to get a new one in order to work on Chrome 59 through 61. You can use both
tokens on a page at once to retain coverage in Chrome 58 while it's still
stable.

New Origin Trial tokens can be requested here.
<https://docs.google.com/a/google.com/forms/d/e/1FAIpQLSfO0_ptFl8r8G0UFhT0xhV17eabG-erUWBDiKSRDTqEZ_9ULQ/viewform>

This is because of the API changes that we've introduced. We don't want
people silently updating the token without checking to ensure that your
content still works with the new API restrictions. As detailed in a
previous email those API changes are:

- VRDisplay.getPose()
- VRDisplay.resetPose()
- VRDisplay.isConnected
- VRDisplayCapabilities.hasOrientation
- VREyeParameters.fieldOfView

These have also been marked as "deprecated" in the WebVR 1.1 spec. They
were removed because no equivalent functionality is planned for WebVR 2.0.

We also encourage you to test the performance of Chrome 59, as our resident
Android optimization guru Klaus has been working his magic and the results
have been great!

One other word of warning: There was a brief period during which we
temporarily disabled WebVR over HTTP while rearchitecting some parts of the
WebVR systems. This should not have affected any Origin Trial use, since
they require HTTPS anyway, but you may encounter some temporary problems
with local development might hit a snag temporarily. (The problem is
already fixed in Canary builds.)

Let us know if you have questions or concerns! Thanks!

--Brandon Jones