Adding WebVR interface to Blink

Source/modules/vr/VRPositionState.idl

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// http://mozvr.github.io/webvr-spec/webvr.html#vrpositionstate
+[
+    RuntimeEnabled=VRDevice,
+    GarbageCollected,
+] interface VRPositionState {
+    readonly attribute double timeStamp;
+    readonly attribute DOMPoint? position;
+    readonly attribute DOMPoint? linearVelocity;
+    readonly attribute DOMPoint? linearAcceleration;
+    readonly attribute DOMPoint? orientation;
+    readonly attribute DOMPoint? angularVelocity;
+    readonly attribute DOMPoint? angularAcceleration;
+};