Make chrome/browser/chromeos/accessibility compile on Athena with use_ash=0

ash/system/chromeos/virtual_keyboard/virtual_keyboard_tray.h

 // Copyright 2014 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_CHROMEOS_VIRTUAL_KEYBOARD_VIRTUAL_KEYBOARD_TRAY_H_
 #define ASH_SYSTEM_CHROMEOS_VIRTUAL_KEYBOARD_VIRTUAL_KEYBOARD_TRAY_H_
 
 #include "ash/system/tray/tray_background_view.h"
 #include "ash/system/tray_accessibility.h"
 #include "ash/system/user/login_status.h"
@@ skipping 21 matching lines @@
       const views::TrayBubbleView* bubble_view) override;
   virtual bool ClickedOutsideBubble() override;
   virtual bool PerformAction(const ui::Event& event) override;
 
   // views::ButtonListener:
   virtual void ButtonPressed(views::Button* sender,
                              const ui::Event& event) override;
 
   // AccessibilityObserver:
   virtual void OnAccessibilityModeChanged(
-      AccessibilityNotificationVisibility notify) override;
+      ui::AccessibilityNotificationVisibility notify) override;
 
  private:
   views::ImageButton* button_;  // Not owned.
 
   DISALLOW_COPY_AND_ASSIGN(VirtualKeyboardTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_CHROMEOS_VIRTUAL_KEYBOARD_VIRTUAL_KEYBOARD_TRAY_H_