Factor out AudioOutputDelegate from AudioRendererHost.

content/browser/renderer_host/media/audio_output_delegate.h

Index: content/browser/renderer_host/media/audio_output_delegate.h
diff --git a/content/browser/renderer_host/media/audio_output_delegate.h b/content/browser/renderer_host/media/audio_output_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..28e75729d8c7cee9abb3cefaa3149724e4f8850e
--- /dev/null
+++ b/content/browser/renderer_host/media/audio_output_delegate.h
@@ -0,0 +1,145 @@
+// 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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_H_
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/common/content_export.h"
+#include "media/audio/audio_output_controller.h"
+
+namespace base {
+class SharedMemory;
+class CancelableSyncSocket;
+}
+
+namespace content {
+class AudioMirroringManager;
+class AudioSyncReader;
+class MediaObserver;
+}
+
+namespace media {
+class AudioLog;
+class AudioParameters;
+}
+
+namespace content {
+
+// This class, except for the AudioOutputDelegate::EventHandler implementation,
+// is operated on the IO thread.
+class CONTENT_EXPORT AudioOutputDelegate
+    : public media::AudioOutputController::EventHandler {
+ public:
+  class CONTENT_EXPORT EventHandler {
+   public:
+    virtual ~EventHandler() {}
+
+    // All these methods are called on the IO thread.
+
+    // Called when the state changes between playing and not playing.
+    virtual void OnStreamStateChanged(bool playing) = 0;
+
+    // Called when construction is finished and the stream is ready for
+    // playout.
+    virtual void OnStreamCreated(int stream_id,
+                                 base::SharedMemory* shared_memory,
+                                 base::CancelableSyncSocket* socket) = 0;
+
+    // Called if stream encounters an error and has become unusable.
+    virtual void OnStreamError(int stream_id) = 0;
+  };
+
+  class Deleter {
+   public:
+    Deleter() = default;
+    explicit Deleter(AudioMirroringManager* mirroring_manager)
+        : mirroring_manager_(mirroring_manager) {}
+    void operator()(AudioOutputDelegate* delegate);
+
+   private:
+    AudioMirroringManager* mirroring_manager_;
+  };
+
+  using UniquePtr = std::unique_ptr<AudioOutputDelegate, Deleter>;
+
+  // The AudioOutputDelegate might issue callbacks until the UniquePtr
+  // destructor finishes, so calling |handler| must be valid until then.
+  static UniquePtr Create(EventHandler* handler,
+                          media::AudioManager* audio_manager,
+                          std::unique_ptr<media::AudioLog> audio_log,
+                          AudioMirroringManager* mirroring_manager,
+                          MediaObserver* media_observer,
+                          int stream_id,
+                          int render_frame_id,
+                          int render_process_id,
+                          const media::AudioParameters& params,
+                          const std::string& output_device_id);
+  ~AudioOutputDelegate() override;
+
+  // TODO(maxmorin): Remove this when crbug.com/647185 is closed.
+  // This function is used to provide control of the audio stream to
+  // WebrtcAudioPrivateGetActiveSinkFunction and others in the webrtc extension
+  // API. Since the controller is shared, this means that it might outlive the
+  // AudioOutputDelegate. In this case, it is still safe to call functions on
+  // the controller, but it will not do anything. The controller is also shared
+  // with AudioStreamMonitor.
+  scoped_refptr<media::AudioOutputController> controller() const {
+    return controller_;
+  }
+
+  int stream_id() const { return stream_id_; }
+
+  // Stream control:
+  void OnPlayStream();
+  void OnPauseStream();
+  void OnSetVolume(double volume);
+
+  // AudioOutputController::EventHandler implementation. These methods may
+  // be called on any thead.
+  void OnControllerCreated() override;
+  void OnControllerPlaying() override;
+  void OnControllerPaused() override;
+  void OnControllerError() override;
+
+ private:
+  AudioOutputDelegate(EventHandler* handler,
+                      media::AudioManager* audio_manager,
+                      std::unique_ptr<media::AudioLog> audio_log,
+                      int stream_id,
+                      int render_frame_id,
+                      int render_process_id,
+                      const media::AudioParameters& params,
+                      const std::string& output_device_id);
+
+  void SendCreatedNotification();
+  void OnError();
+  void UpdatePlayingState(bool playing);
+
+  base::WeakPtr<AudioOutputDelegate> weak_this_;

[DaleCurtis, 2016/12/02 18:20:13]

Should be down with the WeakPtrFactory.

[miu, 2016/12/02 22:57:58]

Put it after the WeakPtrFactory, and then the ctor can initialize this in its
initializer list.

[Max Morin, 2016/12/05 13:53:50]

The WeakPtrFactory must be last (enforced by compiler), so I put the weak ptr
just above it. All other comments have been addressed.

+  // |handler_| is null if we are in the process of destruction. In this case,
+  // we will ignore events from |controller_|.
+  EventHandler* handler_;
+  std::unique_ptr<media::AudioLog> const audio_log_;
+  std::unique_ptr<AudioSyncReader> reader_;
+  scoped_refptr<media::AudioOutputController> controller_;
+  const int stream_id_;
+  const int render_frame_id_;
+  const int render_process_id_;
+
+  // This flag ensures that we only send OnStreamStateChanged notifications
+  // and (de)register with the stream monitor when the state actually changes.
+  bool playing_ = false;
+  base::WeakPtrFactory<AudioOutputDelegate> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputDelegate);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_H_