[Media Router] Notify MRUI of a media status update when it starts observing

chrome/browser/media/router/mojo/media_route_controller.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_MOJO_MEDIA_ROUTE_CONTROLLER_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MOJO_MEDIA_ROUTE_CONTROLLER_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
@@ skipping 26 matching lines @@
   // Observes MediaRouteController for MediaStatus updates. The ownership of a
   // MediaRouteController is shared by its observers.
   class Observer {
    public:
     // Adds itself as an observer to |controller|.
     explicit Observer(scoped_refptr<MediaRouteController> controller);
 
     // Removes itself as an observer if |controller_| is still valid.
     virtual ~Observer();
 
+    // Notifies itself with the latest media status that the controller has
+    // received.
+    void CheckForMediaStatusUpdates();

[mark a. foltz, 2017/05/12 21:00:58]

Is this necessary?

[takumif, 2017/05/12 22:20:58]

Removed.

+
     virtual void OnMediaStatusUpdated(const MediaStatus& status) = 0;
 
     // Returns a reference to the observed MediaRouteController. The reference
     // should not be stored by any object that does not subclass ::Observer.
     scoped_refptr<MediaRouteController> controller() const {
       return controller_;
     }
 
    private:
     friend class MediaRouteController;
@@ skipping 41 matching lines @@
 
  protected:
   ~MediaRouteController() override;
 
  private:
   friend class base::RefCounted<MediaRouteController>;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
+  const base::Optional<MediaStatus>& current_media_status() const {
+    return current_media_status_;
+  }
+
   // Called when the connection between |this| and the MediaControllerPtr or
   // the MediaStatusObserver binding is no longer valid. Notifies
   // |media_router_| and |observers_| to dispose their references to |this|.
   void OnMojoConnectionError();
 
   // The ID of the Media Route that |this| controls.
   const MediaRoute::Id route_id_;
 
   // Handle to the mojom::MediaController that receives media commands.
   mojom::MediaControllerPtr mojo_media_controller_;
 
   // |media_router_| will be notified when the controller is destroyed.
   MediaRouter* const media_router_;
 
   // The binding to observe the out-of-process provider of status updates.
   mojo::Binding<mojom::MediaStatusObserver> binding_;
 
   // Observers that are notified of status updates. The observers share the
   // ownership of the controller through scoped_refptr.
   base::ObserverList<Observer> observers_;
 
   // This becomes false when the controller is invalidated.
   bool is_valid_ = true;
 
+  // The latest media status that the controller has been notified with.
+  base::Optional<MediaStatus> current_media_status_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaRouteController);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MOJO_MEDIA_ROUTE_CONTROLLER_H_