Add a11y virtual keyboard icon when a11y VK is enabled

ash/system/status_area_widget.h

 // Copyright (c) 2012 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 ASH_SYSTEM_STATUS_AREA_WIDGET_H_
 #define ASH_SYSTEM_STATUS_AREA_WIDGET_H_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_types.h"
 #include "ash/system/user/login_status.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 class ShellDelegate;
 class SystemTray;
 class WebNotificationTray;
 
 namespace internal {
 
 class LogoutButtonTray;
+class VirtualKeyboardTray;
 class StatusAreaWidgetDelegate;
 
 class ASH_EXPORT StatusAreaWidget : public views::Widget {
  public:
   static const char kNativeViewName[];
 
   explicit StatusAreaWidget(aura::Window* status_container);
   virtual ~StatusAreaWidget();
 
   // Creates the SystemTray, WebNotificationTray and LogoutButtonTray.
@@ skipping 32 matching lines @@
   // True if any message bubble is shown.
   bool IsMessageBubbleShown() const;
 
   // Overridden from views::Widget:
   virtual void OnNativeWidgetActivationChanged(bool active) OVERRIDE;
 
  private:
   void AddSystemTray();
   void AddWebNotificationTray();
   void AddLogoutButtonTray();
+  void AddVirtualKeyboardTray();
 
   // Weak pointers to View classes that are parented to StatusAreaWidget:
   internal::StatusAreaWidgetDelegate* status_area_widget_delegate_;
   SystemTray* system_tray_;
   WebNotificationTray* web_notification_tray_;
   LogoutButtonTray* logout_button_tray_;
+  VirtualKeyboardTray* virtual_keyboard_tray_;
   user::LoginStatus login_status_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusAreaWidget);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_STATUS_AREA_WIDGET_H_