Use rewriting to make ChromeOS keyboard F<number> keys produce extended keycodes.

chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc

Index: chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
diff --git a/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc b/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
index 51e35f30452fa4cd90b84cacce681c235ccc03c8..4bf72fe8656d330251cfe404cdbe0e8dcc849a3d 100644
--- a/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
+++ b/chrome/browser/ui/webui/options/chromeos/keyboard_handler.cc
@@ -102,7 +102,7 @@ void KeyboardHandler::InitializePage() {
         "options.KeyboardOverlay.showCapsLockOptions", show_options);
   }
 
-  if (chromebook_function_key) {
+  if (chromeos_keyboard && chromebook_function_key) {
     web_ui()->CallJavascriptFunction(
         "options.KeyboardOverlay.showFunctionKeyOptions", show_options);
   }