Add 5 experimental accessibility features on Chrome OS.

chrome/browser/resources/options/browser_options.js

Index: chrome/browser/resources/options/browser_options.js
diff --git a/chrome/browser/resources/options/browser_options.js b/chrome/browser/resources/options/browser_options.js
index 49d7c9b0ed192f60f57f2c2935439d4ea92acca5..a914eba0ea849def3f42f12bae0c1f939dfb48d6 100644
--- a/chrome/browser/resources/options/browser_options.js
+++ b/chrome/browser/resources/options/browser_options.js
@@ -728,6 +728,8 @@ cr.define('options', function() {
         Preferences.getInstance().addEventListener(
             $('accessibility-autoclick-check').getAttribute('pref'),
             updateDelayDropdown);
+        $('experimental_accessibility_features').hidden =
+            !loadTimeData.getBoolean('enableExperimentalAccessibilityFeatures');
       }
 
       // Display management section (CrOS only).