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

ash/system/tray_accessibility.h

Index: ash/system/tray_accessibility.h
diff --git a/ash/system/tray_accessibility.h b/ash/system/tray_accessibility.h
index d9b62066c2a1cc0c3f0c0e3239b5a1e144c705f2..5a6bb5a9151bd2cf3e9ef31da4598bb8785ad863 100644
--- a/ash/system/tray_accessibility.h
+++ b/ash/system/tray_accessibility.h
@@ -36,7 +36,7 @@ class ASH_EXPORT AccessibilityObserver {
 
   // Notifies when accessibilty mode changes.
   virtual void OnAccessibilityModeChanged(
-      AccessibilityNotificationVisibility notify) = 0;
+      ui::AccessibilityNotificationVisibility notify) = 0;
 };
 
 
@@ -124,7 +124,7 @@ class TrayAccessibility : public TrayImageItem,
 
   // Overridden from AccessibilityObserver.
   virtual void OnAccessibilityModeChanged(
-      AccessibilityNotificationVisibility notify) override;
+      ui::AccessibilityNotificationVisibility notify) override;
 
   views::View* default_;
   tray::AccessibilityPopupView* detailed_popup_;