Add mojo interface+impl for audio stream control.

media/mojo/services/mojo_audio_output.h

+// 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 MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_H_
+#define MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_H_
+
+#include <memory>
+#include <string>
+
+// This class handles IPC for single stream by delegating method calls to its

[o1ka, 2017/02/22 13:26:30]

nit "audio output stream"

[Max Morin, 2017/03/02 23:11:32]

Done.

+// AudioOutputDelegate.
+
+#include "base/threading/thread_checker.h"
+#include "media/base/audio_output_delegate.h"
+#include "media/mojo/interfaces/audio_output.mojom.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace media {
+
+class MojoAudioOutput : public mojom::AudioOutput,
+                        public AudioOutputDelegate::EventHandler {
+ public:
+  using CreateDelegateCallback =
+      base::OnceCallback<std::unique_ptr<AudioOutputDelegate>(
+          AudioOutputDelegate::EventHandler*,
+          const AudioParameters&)>;
+  using FinishedCallback = base::OnceCallback<void(mojom::AudioOutput*)>;
+
+  // |create_delegate_callback| is used to obtain an AudioOutputDelegate for the
+  // stream when it's started and |finished_callback| is called when this class
+  // should be removed (stream ended/error).
+  MojoAudioOutput(mojom::AudioOutputRequest request,
+                  CreateDelegateCallback create_delegate_callback,
+                  FinishedCallback finished_callback);
+
+  ~MojoAudioOutput() override;
+
+ private:
+  // mojom::AudioOutput implementation.
+  void Start(const AudioParameters& params,
+             const StartCallback& callback) override;
+  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();
+
+  // The callback for the Start() must be stored until the response is ready.
+  StartCallback start_callback_;
+
+  mojo::Binding<AudioOutput> binding_;
+  CreateDelegateCallback create_delegate_callback_;
+  FinishedCallback finished_callback_;
+  base::ThreadChecker thread_checker_;
+  std::unique_ptr<AudioOutputDelegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoAudioOutput);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MOJO_SERVICES_MOJO_AUDIO_OUTPUT_H_