More user id tracking for mus:

components/mus/ws/window_manager_factory_registry.h

Index: components/mus/ws/window_manager_factory_registry.h
diff --git a/components/mus/ws/window_manager_factory_registry.h b/components/mus/ws/window_manager_factory_registry.h
index 519257deee3267f974fb8ba376a93b89c3d00043..0bb721b77444ed0412d3af7d78116d520fa5fc72 100644
--- a/components/mus/ws/window_manager_factory_registry.h
+++ b/components/mus/ws/window_manager_factory_registry.h
@@ -11,38 +11,64 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "components/mus/public/interfaces/window_manager_factory.mojom.h"
+#include "components/mus/ws/user_id_tracker_observer.h"
 
 namespace mus {
 namespace ws {
 
 class ConnectionManager;
+class UserIdTracker;
+class WindowManagerFactoryRegistryObserver;
 class WindowManagerFactoryService;
 
+namespace test {
+class WindowManagerFactoryRegistryTestApi;
+}
+
 // WindowManagerFactoryRegistry tracks the set of registered
 // WindowManagerFactoryServices.
-class WindowManagerFactoryRegistry {
+class WindowManagerFactoryRegistry : public UserIdTrackerObserver {
  public:
-  explicit WindowManagerFactoryRegistry(ConnectionManager* connection_manager);
-  ~WindowManagerFactoryRegistry();
+  explicit WindowManagerFactoryRegistry(ConnectionManager* connection_manager,
+                                        UserIdTracker* tracker);
+  ~WindowManagerFactoryRegistry() override;
 
   void Register(
-      uint32_t user_id,
+      UserId user_id,
       mojo::InterfaceRequest<mojom::WindowManagerFactoryService> request);
 
   std::vector<WindowManagerFactoryService*> GetServices();
 
+  void AddObserver(WindowManagerFactoryRegistryObserver* observer);
+  void RemoveObserver(WindowManagerFactoryRegistryObserver* observer);
+
  private:
   friend class WindowManagerFactoryService;
+  friend class test::WindowManagerFactoryRegistryTestApi;
+
+  void AddServiceImpl(scoped_ptr<WindowManagerFactoryService> service);
 
+  bool ContainsServiceForUser(UserId user_id) const;
   void OnWindowManagerFactoryConnectionLost(
       WindowManagerFactoryService* service);
-  void OnWindowManagerFactorySet();
+  void OnWindowManagerFactorySet(WindowManagerFactoryService* service);
 
+  // UserIdTrackerObserver:
+  void OnActiveUserIdChanged(UserId id) override;
+  void OnUserIdAdded(UserId id) override;
+  void OnUserIdRemoved(UserId id) override;
+
+  // Set to true the first time a valid factory has been found.
+  bool got_valid_factory_ = false;
+  UserIdTracker* id_tracker_;
   ConnectionManager* connection_manager_;
 
   std::vector<scoped_ptr<WindowManagerFactoryService>> services_;
 
+  base::ObserverList<WindowManagerFactoryRegistryObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowManagerFactoryRegistry);
 };