MD Settings: Add remaining buttons to keyboard subpage

chrome/browser/ui/webui/settings/chromeos/device_keyboard_handler.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_DEVICE_KEYBOARD_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_DEVICE_KEYBOARD_HANDLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/ui/webui/settings/settings_page_ui_handler.h"
 #include "ui/events/devices/input_device_event_observer.h"
@@ skipping 22 matching lines @@
   // SettingsPageUIHandler implementation.
   void RegisterMessages() override;
 
   // ui::InputDeviceEventObserver implementation.
   void OnKeyboardDeviceConfigurationChanged() override;
 
  private:
   // Initializes the page with the current keyboard information.
   void HandleInitialize(const base::ListValue* args);
 
+  // Shows the Ash keyboard shortcuts overlay.
+  void HandleShowKeyboardShortcutsOverlay(const base::ListValue* args) const;
+
   // Shows or hides the Caps Lock and Diamond key settings based on whether the
   // system status.
   void UpdateShowKeys() const;
 
   Profile* profile_;  // Weak pointer.
 
   DISALLOW_COPY_AND_ASSIGN(KeyboardHandler);
 };
 
 }  // namespace settings
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_SETTINGS_CHROMEOS_DEVICE_KEYBOARD_HANDLER_H_