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..2b63e80fc2d4970bc5dc83e69e9613109dd99ae9 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).