Control the VrShell content quad via the HTML UI.

chrome/browser/resources/vr_shell/vr_shell_ui_api.js

 // 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.
 
 var api = (function() {
   'use strict';
 
   /**
    * Enumeration of scene update commands.
    * @enum {number}
@@ skipping 88 matching lines @@
     chrome.send('domLoaded');
   }
 
   /**
    * Represents updates to UI element properties. Any properties set on this
    * object are relayed to an underlying native element via scene command.
    * Properties that are not set on this object are left unchanged.
    */
   class UiElementUpdate {
 
+    setIsContentQuad() {
+      this.contentQuad = true;
+    }
+
     /**
      * Specify a parent for this element. If set, this element is positioned
      * relative to its parent element, rather than absolutely. This allows
      * elements to automatically move with a parent.
      */
     setParentId(id) {
       this.parentId = id;
     }
 
     /**
@@ skipping 177 matching lines @@
     Action: Action,
     Mode: Mode,
     getContentElementId: getContentElementId,
     UiElement: UiElement,
     UiElementUpdate: UiElementUpdate,
     Animation: Animation,
     doAction: doAction,
     domLoaded: domLoaded,
   };
 })();