Decouple VR Shell DPR and CSS size from Physical Displays.

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 83 matching lines @@
 
   /**
    * Notify native scene management that DOM loading has completed, at the
    * specified page size.
    */
   function domLoaded() {
     chrome.send('domLoaded');
   }
 
   /**
+   * Sets the CSS size for this page.
+   */
+  function setUiCssSize(width, height, dpr) {
+    chrome.send('setUiCssSize', [width, height, dpr]);
+  }
+
+  /**
    * 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;
     }
 
@@ skipping 185 matching lines @@
     Easing: Easing,
     Command: Command,
     Action: Action,
     Mode: Mode,
     getContentElementId: getContentElementId,
     UiElement: UiElement,
     UiElementUpdate: UiElementUpdate,
     Animation: Animation,
     doAction: doAction,
     domLoaded: domLoaded,
+    setUiCssSize: setUiCssSize,
   };
 })();