[Media Router] Custom Controls 1 - Add MediaStatus, MediaRouteController, and mojo interfaces

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 <unordered_set>
+
+#include "base/observer_list.h"
+#include "chrome/browser/media/router/media_route.h"
+#include "chrome/browser/media/router/media_status.h"
+#include "chrome/browser/media/router/mojo/media_controller.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace base {
+class TimeDelta;
+}
+
+namespace media_router {
+
+class MediaRouteStatusObserver;
+
+// A controller for a MediaRoute. Forwards commands for controlling the route to
+// an out-of-process controller. Notifies its observers whenever there is a
+// change in the route's MediaStatus. Gets destroyed when the route is
+// terminated or the last observer of |this| is removed.
+class MediaRouteController : public mojom::MediaStatusObserver {

[mark a. foltz, 2017/03/13 18:22:31]

What would use this class?  I thought that the controllers would be implemented
as part of the component MRPs?

On the browser side it seems like the UI could interact with the
mojom::MediaControllerPtr directly as all this class does is forward calls to
it.

+ public:
+  // |this| will forward media commands to |media_controller|.
+  // |destroyer_callback| will be called when the last observer of |this| is
+  // removed. |destroyer_callback| must destroy |this|.
+  MediaRouteController(mojom::MediaControllerPtr media_controller,
+                       base::Closure destroyer_callback);
+  ~MediaRouteController() override;
+
+  // Media controller methods for forwarding commands to |media_controller_|.
+  void Play();
+  void Pause();
+  void Seek(base::TimeDelta time);
+  void SetMute(bool mute);
+  void SetVolume(float volume);
+
+  void AddObserver(MediaRouteStatusObserver* observer);
+  // Calls |destroyer_callback_| if the last observer is removed.
+  void RemoveObserver(MediaRouteStatusObserver* observer);
+
+  // mojom::MediaStatusObserver:
+  void OnMediaStatusUpdated(const MediaStatus& status) override;
+
+  // Returns a mojo pointer bound to |this| by |binding_|. If |binding_| is
+  // already set, then the previous binding gets invalidated.
+  mojom::MediaStatusObserverPtr GetObserverPtr();
+
+ private:
+  // Gets called when |this| should no longer exist. Needs to destroy |this|.
+  base::Closure destroyer_callback_;
+
+  // The out-of-process controller that |this| forwards commands to.
+  mojom::MediaControllerPtr media_controller_;
+
+  // The binding to observe the out-of-process provider of status updates.
+  mojo::Binding<mojom::MediaStatusObserver> binding_;
+
+  // Observers that |this| notifies of status updates.
+  base::ObserverList<MediaRouteStatusObserver> observers_;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_MOJO_MEDIA_ROUTE_CONTROLLER_H_