Adds in-out easing type.

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 = {};
 
 /**
  * Enumeration of scene update commands.
  * @enum {number}
  * @const
@@ skipping 323 matching lines @@
 
 /**
  * Enumeration of easing type.
  * @enum {number}
  * @const
  */
 api.EasingType = {
   'LINEAR': 0,
   'CUBICBEZIER': 1,
   'EASEIN': 2,
-  'EASEOUT': 3
+  'EASEOUT': 3,
+  'EASEINOUT': 4
 };
 
 /** @const */ var DEFAULT_EASING_POW = 2;
 /** @const */ var DEFAULT_CUBIC_BEZIER_P1X = 0.25;
 /** @const */ var DEFAULT_CUBIC_BEZIER_P1Y = 0;
 /** @const */ var DEFAULT_CUBIC_BEZIER_P2X = 0.75;
 /** @const */ var DEFAULT_CUBIC_BEZIER_P2Y = 1;
 
 /**
  * Abstract easing base class.
@@ skipping 32 matching lines @@
   }
 }
 
 api.OutEasing = class extends api.Easing {
   constructor(pow = DEFAULT_EASING_POW) {
     super(api.EasingType.EASEOUT);
     this.pow = pow;
   }
 }
 
+api.InOutEasing = class extends api.Easing {
+  constructor(pow = DEFAULT_EASING_POW) {

[cjgrant, 2017/02/16 20:54:07]

nit: On POW vs POWER:

https://engdoc.corp.google.com/eng/doc/devguide/cpp/styleguide.shtml?cl=head#...

Probably not worth changing this here; just an FYI for code you add later.

+    super(api.EasingType.EASEINOUT);
+    this.pow = pow;
+  }
+}
+
 /**
  * Base animation class. An animation can vary only one object property.
  * @struct
  */
 api.Animation = class {
   constructor(elementId, durationMs) {
     /** @private {number} */
     this.id = -1;
     /** @private {number} */
     this.meshId = elementId;
@@ skipping 222 matching lines @@
     if ('updateTab' in dict) {
       this.onUpdateTab(dict['updateTabs']);
     }
     if ('removeTab' in dict) {
       this.onRemoveTab(dict['removeTab']);
     }
 
     this.onCommandHandlerFinished()
   }
 };