ash: Fix system tray avatar not updated regression

ash/common/system/tray/system_tray_notifier.cc

Index: ash/common/system/tray/system_tray_notifier.cc
diff --git a/ash/common/system/tray/system_tray_notifier.cc b/ash/common/system/tray/system_tray_notifier.cc
index bfff62a7b00db2e8a51215ac834e2fdd5e2067ed..6c6d37b5da65959265a837d627fecbed626ae5a3 100644
--- a/ash/common/system/tray/system_tray_notifier.cc
+++ b/ash/common/system/tray/system_tray_notifier.cc
@@ -18,7 +18,6 @@
 #include "ash/common/system/chromeos/virtual_keyboard/virtual_keyboard_observer.h"
 #include "ash/common/system/date/clock_observer.h"
 #include "ash/common/system/ime/ime_observer.h"
-#include "ash/common/system/user/user_observer.h"
 
 namespace ash {
 
@@ -262,24 +261,6 @@ void SystemTrayNotifier::NotifyTracingModeChanged(bool value) {
     observer.OnTracingModeChanged(value);
 }
 
-void SystemTrayNotifier::AddUserObserver(UserObserver* observer) {
-  user_observers_.AddObserver(observer);
-}
-
-void SystemTrayNotifier::RemoveUserObserver(UserObserver* observer) {
-  user_observers_.RemoveObserver(observer);
-}
-
-void SystemTrayNotifier::NotifyUserUpdate() {
-  for (auto& observer : user_observers_)
-    observer.OnUserUpdate();
-}
-
-void SystemTrayNotifier::NotifyUserAddedToSession() {
-  for (auto& observer : user_observers_)
-    observer.OnUserAddedToSession();
-}
-
 void SystemTrayNotifier::AddVirtualKeyboardObserver(
     VirtualKeyboardObserver* observer) {
   virtual_keyboard_observers_.AddObserver(observer);