Add power-user keyboard mode for ChromeOS with Search key acting as a typical Fn key.

chrome/browser/resources/options/chromeos/keyboard_overlay.js

Index: chrome/browser/resources/options/chromeos/keyboard_overlay.js
diff --git a/chrome/browser/resources/options/chromeos/keyboard_overlay.js b/chrome/browser/resources/options/chromeos/keyboard_overlay.js
index f6df30d84985125f66dc54268b3efbdaf193cc3f..98fa0997ec7d03b4f4528422bbe32c76c5481f99 100644
--- a/chrome/browser/resources/options/chromeos/keyboard_overlay.js
+++ b/chrome/browser/resources/options/chromeos/keyboard_overlay.js
@@ -27,11 +27,20 @@ cr.define('options', function() {
     showCapsLockOptions_: function(show) {
       $('caps-lock-remapping-section').hidden = !show;
     },
+
+    /**
+     * Show/hide the function key remapping section.
+     * @private
+     */
+    showFunctionKeyOptions_: function(show) {
+      $('function-key-remapping-section').hidden = !show;
+    },
   };
 
   // Forward public APIs to private implementations.
   [
     'showCapsLockOptions',
+    'showFunctionKeyOptions',
   ].forEach(function(name) {
     KeyboardOverlay[name] = function() {
       var instance = KeyboardOverlay.getInstance();