Enable WebVR origin trial experiments.

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

 // Copyright 2016 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#vrdisplaycapabilities
 [
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VRDisplayCapabilities {
   // Whether or not the VR display is capable of reporting user orientation.
   readonly attribute boolean hasOrientation;
 
   // Whether or not the VR display is capable of reporting user position.
   // If false position may still be reported using simulated values like
   // neck modeling.
   readonly attribute boolean hasPosition;
 
   // Whether or not the VRDisplay is separate from the device’s primary display.
   // If presenting VR content will obscure other content on the device, this
   // should be false. When false VR content should not be mirrored.
   readonly attribute boolean hasExternalDisplay;
 
   // Whether or not the VRDisplay is capable of presenting content to an HMD or
   // similar device. Can be used to indicate “magic window” devices that are
   // capable of 6DoF tracking but for which requestPresent is not meaningful. If
   // false then calls to requestPresent should always fail, and getEyeParameters
   // should return null.
   readonly attribute boolean canPresent;
 
   // The maximum length of the array that VRDisplay.requestPresent will accept.
   readonly attribute unsigned long maxLayers;
 };