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

third_party/WebKit/Source/modules/vr/VRDisplay.idl

Index: third_party/WebKit/Source/modules/vr/VRDisplay.idl
diff --git a/third_party/WebKit/Source/modules/vr/VRDisplay.idl b/third_party/WebKit/Source/modules/vr/VRDisplay.idl
index 2a00e74454067a232042a7d6d445792280fad8bf..1d6fca88215700ece998479b0dd262fc21fe3307 100644
--- a/third_party/WebKit/Source/modules/vr/VRDisplay.idl
+++ b/third_party/WebKit/Source/modules/vr/VRDisplay.idl
@@ -17,9 +17,9 @@ enum VREye {
     readonly attribute unsigned long displayId;
 
     // A user-readable name identifying the device.
-    readonly attribute DOMString displayName;
+    [MeasureAs=VRDisplayDisplayName] readonly attribute DOMString displayName;
 
-    readonly attribute boolean isConnected;
+    [MeasureAs=VRDisplayIsConnected] readonly attribute boolean isConnected;
     readonly attribute boolean isPresenting;
 
     // [Constant]?
@@ -29,7 +29,7 @@ enum VREye {
 
     boolean getFrameData(VRFrameData frameData);
     [DeprecateAs=VRDeprecatedGetPose] VRPose getPose();
-    void resetPose();
+    [MeasureAs=VRDisplayResetPose] void resetPose();
 
     attribute double depthNear;
     attribute double depthFar;