Change userid from a uint32_t to a string guid

components/mus/ws/user_id_tracker_observer.h

Index: components/mus/ws/user_id_tracker_observer.h
diff --git a/components/mus/ws/user_id_tracker_observer.h b/components/mus/ws/user_id_tracker_observer.h
index d6b5a86b5285e4f8a81657adf6588995f5430cee..840c410bf4c0ce018c8b6b6a3651edfa6ff15fa5 100644
--- a/components/mus/ws/user_id_tracker_observer.h
+++ b/components/mus/ws/user_id_tracker_observer.h
@@ -14,9 +14,9 @@ namespace ws {
 
 class UserIdTrackerObserver {
  public:
-  virtual void OnActiveUserIdChanged(UserId id) = 0;
-  virtual void OnUserIdAdded(UserId id) = 0;
-  virtual void OnUserIdRemoved(UserId id) = 0;
+  virtual void OnActiveUserIdChanged(const UserId& id) = 0;
+  virtual void OnUserIdAdded(const UserId& id) = 0;
+  virtual void OnUserIdRemoved(const UserId& id) = 0;
 
  protected:
   virtual ~UserIdTrackerObserver() {}