Hi, @Bill and @Anna, I'm DonnaWu from Intel Web team, trying to find something to do on WebVR/XR. After some investigation, I found this issue is caused by nonsupport of relative orientation on Windows(#730440). If the sensor type is changed to "ABSOLUTE_ORIENTATION_xxx", the magic window will work will on Windows.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d2d58cb0b589b287d166bd3fb1e508a2249cb017

commit d2d58cb0b589b287d166bd3fb1e508a2249cb017
Author: Anna Offenwanger <offenwanger@chromium.org>
Date: Fri May 11 18:23:45 2018

Special casing windows for VR orientation device

Chrome for windows does not support the relative orientation sensor, so
if we are on windows, use the absolute sensor.

Bug: 820308
Change-Id: I3630ae8417839d94bedf8901b4f1509ed8e071d0
Reviewed-on: https://chromium-review.googlesource.com/1050372
Commit-Queue: Anna Offenwanger <offenwanger@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557947}
[modify] https://crrev.com/d2d58cb0b589b287d166bd3fb1e508a2249cb017/device/vr/orientation/orientation_device.cc
[modify] https://crrev.com/d2d58cb0b589b287d166bd3fb1e508a2249cb017/device/vr/orientation/orientation_device.h
[modify] https://crrev.com/d2d58cb0b589b287d166bd3fb1e508a2249cb017/device/vr/orientation/orientation_device_provider_unittest.cc
[modify] https://crrev.com/d2d58cb0b589b287d166bd3fb1e508a2249cb017/device/vr/orientation/orientation_device_unittest.cc

Removing Blink>WebVR component and assigning to Blink>WebXR 

Removing Blink>WebVR component and assigning to Blink>WebXR 

Removing Internals>VR component and assigning to Internals>XR

This issue is currently blocked on special casing the screen orientation correction for windows devices (see http://crbug.com/811453) as well as the quality of the data received from sensors on the only device we've gotten ahold of to test on so far. 
The motion on that device (a windows tablet) was very choppy, so we may need to add some data smoothing to make the experience of sufficient quality to ship.

Screen orientation fix will need to go in here: https://cs.chromium.org/chromium/src/device/vr/orientation/orientation_device.cc?sq=package:chromium&dr=CSs&g=0&l=178