Add UseCounters to evaluate usage and risk with upcoming WebVR spec changes.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index cedb21adf3f309a81938b89eeb221861b18f735c..4bc79fb5e9e46f4e952826528398347982d477f1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -93348,6 +93348,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1855" label="HTMLMediaElementControlsListNoFullscreen"/>
   <int value="1856" label="HTMLMediaElementControlsListNoRemotePlayback"/>
   <int value="1857" label="PointerEventClickRetargetCausedByCapture"/>
+  <int value="1858" label="VRDisplayIsConnected"/>
+  <int value="1859" label="VRDisplayResetPose"/>
+  <int value="1860" label="VRDisplayCapabilitiesHasOrientation"/>
+  <int value="1861" label="VRDisplayDisplayName"/>
+  <int value="1862" label="VREyeParametersOffset"/>
+  <int value="1863" label="VRPoseLinearVelocity"/>
+  <int value="1864" label="VRPoseLinearAcceleration"/>
+  <int value="1865" label="VRPoseAngularVelocity"/>
+  <int value="1866" label="VRPoseAngularAcceleration"/>
 </enum>
 
 <enum name="FetchRequestMode" type="int">