Add deprecation messages to deprecated parts of the WebVR API.

third_party/WebKit/Source/modules/vr/VREyeParameters.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#eyeparameters
 [
     RuntimeEnabled=WebVR,
 ] interface VREyeParameters {
   /* These values will vary after a FOV has been set */
   readonly attribute Float32Array offset;
-  readonly attribute VRFieldOfView fieldOfView;
+  [DeprecateAs=VRDeprecatedFieldOfView] readonly attribute VRFieldOfView fieldOfView;
   readonly attribute unsigned long renderWidth;
   readonly attribute unsigned long renderHeight;
 };