Remove usage of FOR_EACH_OBSERVER macro in services/

services/ui/ws/user_id_tracker.cc

Index: services/ui/ws/user_id_tracker.cc
diff --git a/services/ui/ws/user_id_tracker.cc b/services/ui/ws/user_id_tracker.cc
index 3b3e198462ce26586ab62f5bf13d6786d952e96d..f547b5893113cdacd599dc18796888ceeb0b7aa5 100644
--- a/services/ui/ws/user_id_tracker.cc
+++ b/services/ui/ws/user_id_tracker.cc
@@ -28,8 +28,8 @@ void UserIdTracker::SetActiveUserId(const UserId& id) {
 
   const UserId previously_active_id = active_id_;
   active_id_ = id;
-  FOR_EACH_OBSERVER(UserIdTrackerObserver, observers_,
-                    OnActiveUserIdChanged(previously_active_id, id));
+  for (auto& observer : observers_)
+    observer.OnActiveUserIdChanged(previously_active_id, id);
 }
 
 void UserIdTracker::AddUserId(const UserId& id) {
@@ -37,13 +37,15 @@ void UserIdTracker::AddUserId(const UserId& id) {
     return;
 
   ids_.insert(id);
-  FOR_EACH_OBSERVER(UserIdTrackerObserver, observers_, OnUserIdAdded(id));
+  for (auto& observer : observers_)
+    observer.OnUserIdAdded(id);
 }
 
 void UserIdTracker::RemoveUserId(const UserId& id) {
   DCHECK(IsValidUserId(id));
   ids_.erase(id);
-  FOR_EACH_OBSERVER(UserIdTrackerObserver, observers_, OnUserIdRemoved(id));
+  for (auto& observer : observers_)
+    observer.OnUserIdRemoved(id);
 }
 
 void UserIdTracker::AddObserver(UserIdTrackerObserver* observer) {