Adds in-out easing type.

chrome/browser/resources/vr_shell/vr_shell_ui.js

Index: chrome/browser/resources/vr_shell/vr_shell_ui.js
diff --git a/chrome/browser/resources/vr_shell/vr_shell_ui.js b/chrome/browser/resources/vr_shell/vr_shell_ui.js
index 283434ce81bb13e6ccda3378b6c023d0dad0d6f9..591615dda94ba4975553d2fe7525787c82d5222b 100644
--- a/chrome/browser/resources/vr_shell/vr_shell_ui.js
+++ b/chrome/browser/resources/vr_shell/vr_shell_ui.js
@@ -96,9 +96,11 @@ var vrShellUi = (function() {
       let anim;
       anim = new api.Animation(this.elementId, ANIM_DURATION);
       anim.setTranslation(0, y, z);
+      anim.setEasing(new api.InOutEasing());
       ui.addAnimation(anim);
       anim = new api.Animation(this.elementId, ANIM_DURATION);
       anim.setSize(height * this.SCREEN_RATIO, height);
+      anim.setEasing(new api.InOutEasing());
       ui.addAnimation(anim);
     }