Add mojo interface+impl for audio stream control.

media/mojo/services/mojo_audio_output_stream.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 MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_STREAM_H_
+#define MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_STREAM_H_
+
+#include <memory>
+#include <string>
+
+#include "base/threading/thread_checker.h"
+#include "media/audio/audio_output_delegate.h"
+#include "media/mojo/interfaces/audio_output_stream.mojom.h"
+#include "media/mojo/services/media_mojo_export.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace media {
+
+// This class handles IPC for single audio output stream by delegating method
+// calls to its AudioOutputDelegate.
+class MEDIA_MOJO_EXPORT MojoAudioOutputStream
+    : public mojom::AudioOutputStream,
+      public AudioOutputDelegate::EventHandler {
+ public:
+  using StreamCreatedCallback =
+      mojom::AudioOutputStreamProvider::AcquireCallback;
+  using CreateDelegateCallback =
+      base::OnceCallback<std::unique_ptr<AudioOutputDelegate>(
+          AudioOutputDelegate::EventHandler*)>;
+
+  // |create_delegate_callback| is used to obtain an AudioOutputDelegate for the
+  // stream in the constructor. |stream_created_callback| is called when the
+  // stream has been initialized. |deleter_callback| is called when this class
+  // should be removed (stream ended/error). |deleter_callback| is required to
+  // destroy |this| synchronously.
+  MojoAudioOutputStream(mojom::AudioOutputStreamRequest request,
+                        CreateDelegateCallback create_delegate_callback,
+                        StreamCreatedCallback stream_created_callback,
+                        base::OnceClosure deleter_callback);
+
+  ~MojoAudioOutputStream() override;
+
+ private:
+  // mojom::AudioOutputStream implementation.
+  void Play() override;
+  void Pause() override;
+  void SetVolume(double volume) override;
+
+  // AudioOutputDelegate::EventHandler implementation.
+  void OnStreamCreated(int stream_id,
+                       base::SharedMemory* shared_memory,
+                       base::CancelableSyncSocket* foreign_socket) override;
+  void OnStreamError(int stream_id) override;
+
+  // Closes connection to client and notifies owner.
+  void OnError();
+
+  StreamCreatedCallback stream_created_callback_;
+  base::OnceClosure deleter_callback_;
+  mojo::Binding<AudioOutputStream> binding_;
+  base::ThreadChecker thread_checker_;
+  std::unique_ptr<AudioOutputDelegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoAudioOutputStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_STREAM_H_