The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/96ac883d24d719a63645a9374c4a555748eab3f8

commit 96ac883d24d719a63645a9374c4a555748eab3f8
Author: tiborg <tiborg@chromium.org>
Date: Wed May 24 20:45:14 2017

Prevent exiting presentation if triggering DON while presenting.

BUG= 718133 

Review-Url: https://codereview.chromium.org/2864363005
Cr-Commit-Position: refs/heads/master@{#474409}

[modify] https://crrev.com/96ac883d24d719a63645a9374c4a555748eab3f8/chrome/browser/android/vr_shell/vr_shell_delegate.cc
[modify] https://crrev.com/96ac883d24d719a63645a9374c4a555748eab3f8/chrome/browser/android/vr_shell/vr_shell_delegate.h
[modify] https://crrev.com/96ac883d24d719a63645a9374c4a555748eab3f8/device/vr/vr_service.mojom
[modify] https://crrev.com/96ac883d24d719a63645a9374c4a555748eab3f8/third_party/WebKit/Source/modules/vr/VRDisplay.cpp

Hi Tibor, does a blocking issue mean it fixed but still won't work until the blocking issue is resolved? 

Also I'm unclear on what is the expected behavior. When the  device is in the middle of a WebVR presentation, it's removed from the headset, then placed in the headset again (NFC scan again). Should it stay in the WebVR presentation or enter Chrome VR? 

Thanks!

David, blocking means this issue is preventing a different issue from being fixed, but this one itself is fixed and verifiable.

The expected behaviour is that nothing at all happens on headset insertion if you're already in VR, so if you're presenting you stay presenting, and if you're browsing the web in VR you stay browsing the web in VR.

Verified that re-scanning NFC after presenting WebVR or in Chrome VR has no effect.

Chrome: 64.0.3256.0, Pixel XL