Convert TrayAccessibility to wm common types

ash/common/system/tray/wm_system_tray_notifier.cc

Index: ash/common/system/tray/wm_system_tray_notifier.cc
diff --git a/ash/common/system/tray/wm_system_tray_notifier.cc b/ash/common/system/tray/wm_system_tray_notifier.cc
index 50d4566688b1edc04c733b72a2e845ec22e497f8..81289493fbf441c85fe70c7f4adc9a969912a39b 100644
--- a/ash/common/system/tray/wm_system_tray_notifier.cc
+++ b/ash/common/system/tray/wm_system_tray_notifier.cc
@@ -4,6 +4,7 @@
 
 #include "ash/common/system/tray/wm_system_tray_notifier.h"
 
+#include "ash/common/system/accessibility_observer.h"
 #include "ash/common/system/date/clock_observer.h"
 #include "ash/common/system/update/update_observer.h"
 
@@ -13,6 +14,16 @@ WmSystemTrayNotifier::WmSystemTrayNotifier() {}
 
 WmSystemTrayNotifier::~WmSystemTrayNotifier() {}
 
+void WmSystemTrayNotifier::AddAccessibilityObserver(
+    AccessibilityObserver* observer) {
+  accessibility_observers_.AddObserver(observer);
+}
+
+void WmSystemTrayNotifier::RemoveAccessibilityObserver(
+    AccessibilityObserver* observer) {
+  accessibility_observers_.RemoveObserver(observer);
+}
+
 void WmSystemTrayNotifier::AddClockObserver(ClockObserver* observer) {
   clock_observers_.AddObserver(observer);
 }
@@ -29,6 +40,12 @@ void WmSystemTrayNotifier::RemoveUpdateObserver(UpdateObserver* observer) {
   update_observers_.RemoveObserver(observer);
 }
 
+void WmSystemTrayNotifier::NotifyAccessibilityModeChanged(
+    ui::AccessibilityNotificationVisibility notify) {
+  FOR_EACH_OBSERVER(AccessibilityObserver, accessibility_observers_,
+                    OnAccessibilityModeChanged(notify));
+}
+
 void WmSystemTrayNotifier::NotifyRefreshClock() {
   FOR_EACH_OBSERVER(ClockObserver, clock_observers_, Refresh());
 }