The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c

commit 5f3c3c8f4bd093a1ca0540ee7757a148531ef60c
Author: Bill Orr <billorr@chromium.org>
Date: Thu Apr 12 08:20:09 2018

Add UseCounters to measure usage of WebXR

TBR=vollick@chromium.org
BUG= 824825 

Change-Id: I22bb8ca8287ba4d774d56fe48c66f5d0fd25418d
Reviewed-on: https://chromium-review.googlesource.com/1003139
Commit-Queue: Klaus Weidner <klausw@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550101}
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/third_party/blink/public/platform/web_feature.mojom
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/third_party/blink/renderer/modules/vr/navigator_vr.idl
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/third_party/blink/renderer/modules/xr/xr.idl
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/third_party/blink/renderer/modules/xr/xr_device.idl
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/third_party/blink/renderer/modules/xr/xr_session.idl
[modify] https://crrev.com/5f3c3c8f4bd093a1ca0540ee7757a148531ef60c/tools/metrics/histograms/enums.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/594ebee42b3eed5553f81536b6e9fdf29b392b2a

commit 594ebee42b3eed5553f81536b6e9fdf29b392b2a
Author: Bill Orr <billorr@chromium.org>
Date: Tue May 01 00:52:27 2018

Expand WebXR UKMs to include WebXR

WebXR UKMs were designed to cover both WebVR usage and WebXR usage,
but were only hooked up for WebVR. Additionally, this change adds
additional UKM metrics for differentiating WebXR from WebVR, and
learning about gamepad vs. WebXR input usage.

BUG= 824825 

Change-Id: I4be3de178ba2dddad428dae7444313ea3624f4cd
Reviewed-on: https://chromium-review.googlesource.com/1008171
Commit-Queue: Bill Orr <billorr@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554945}
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/services/metrics/public/cpp/ukm_recorder.h
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/gamepad/DEPS
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/gamepad/navigator_gamepad.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/vr/navigator_vr.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/vr/navigator_vr.h
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/DEPS
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr.h
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr_device.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr_device.h
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr_presentation_frame.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr_session.cc
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/third_party/blink/renderer/modules/xr/xr_session.h
[modify] https://crrev.com/594ebee42b3eed5553f81536b6e9fdf29b392b2a/tools/metrics/ukm/ukm.xml