mash: Change the MediaDelegate to a Media{Controller,Client}.

ash/common/media_controller.h

Index: ash/common/media_controller.h
diff --git a/ash/common/media_controller.h b/ash/common/media_controller.h
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+++ b/ash/common/media_controller.h
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+// Copyright 2016 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 ASH_COMMON_MEDIA_CONTROLLER_H_
+#define ASH_COMMON_MEDIA_CONTROLLER_H_
+
+#include "ash/public/interfaces/media.mojom.h"
+#include "base/macros.h"
+#include "mojo/public/cpp/bindings/associated_binding.h"
+#include "mojo/public/cpp/bindings/binding_set.h"
+
+namespace ash {
+
+// Forwards notifications from the MediaController to observers.
+class MediaCaptureObserver {
+ public:
+  // Called when media capture state has changed.
+  virtual void OnMediaCaptureChanged(
+      const std::vector<mojom::MediaCaptureState>& capture_states) = 0;
+
+ protected:
+  virtual ~MediaCaptureObserver() {}
+};
+
+// Provides the MediaController interface to the outside world. This lets a
+// consumer of ash provide a MediaClient, which we will dispatch to if one has
+// been provided to us.
+class MediaController : public mojom::MediaController,
+                        public mojom::MediaClient {
+ public:
+  MediaController();
+  ~MediaController() override;
+
+  void BindRequest(mojom::MediaControllerRequest request);
+
+  void AddObserver(MediaCaptureObserver* observer);
+  void RemoveObserver(MediaCaptureObserver* observer);
+
+  // mojom::MediaClient:
+  void HandleMediaNextTrack() override;
+  void HandleMediaPlayPause() override;
+  void HandleMediaPrevTrack() override;
+  void RequestCaptureState() override;
+
+ private:
+  friend class MultiProfileMediaTrayItemTest;
+
+  // mojom::MediaController:
+  void SetClient(mojom::MediaClientAssociatedPtrInfo client) override;
+  void NotifyCaptureState(
+      const std::vector<mojom::MediaCaptureState>& capture_states) override;
+
+  mojo::BindingSet<mojom::MediaController> bindings_;
+
+  mojom::MediaClientAssociatedPtr client_;
+
+  base::ObserverList<MediaCaptureObserver> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_MEDIA_CONTROLLER_H_