Add AudioStreamRegistry. Move stream counting logic

content/browser/renderer_host/media/audio_output_delegate.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 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/browser/renderer_host/media/audio_stream_registry.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 media::AudioOutputController::EventHandler,
+      public AudioStreamRegistry::Stream {
  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 CONTENT_EXPORT 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,
+                          AudioStreamRegistry* stream_registry,
                           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_; }
 
+#if BUILDFLAG(ENABLE_WEBRTC)
+  void EnableDebugRecording(const base::FilePath& base_file_name) override;

[o1ka, 2016/12/22 10:46:51]

Oh, I just realized. AusioStreamRegistry will live in the audio process, right?
Enable/Disable debug recording per stream should be a process-local operation.
And AuiodOutputDelegate is basically our representation of IPC. So, it looks
like AudioOutputController is one who should be AusioStreamRegistry::Stream.

[Max Morin, 2017/01/09 15:34:23]

I think AudioStreamRegistry will live in the browser process. The stream
counting is needed for RPH to know if the renderer should be backgrounded, and I
don't think we want the mojo jump every time we check that. Possibly,
AudioStreamRegistry just gets updates to a HasAudio bit from the audio process.
The stream counting (for stats) can be done completely in the browser process.
Finally, debug recording is a bit tricky (since we'll need to supply file
descriptors to the audio process). We might have the stream factories in the
audio process return two objects: an (Input/Output)Stream which the browser
sends to renderer and another interface to the stream which the browser keeps
with (Enable/Disable)DebugRecording (and maybe something else).

It doesn't matter much if AudioOutputDelegate or AudioOutputController is the
Stream, I picked AudioOutputDelegate because it lives on the IO thread, so we
have an easier time with thread management like this.

[o1ka, 2017/01/10 11:47:40]

Ah ok, sounds good. Stream interfaces need to be figured, not sure how well it
will look in Mojo world.

+  void DisableDebugRecording() override;
+#endif  // BUILDFLAG(ENABLE_WEBRTC)
+
   // 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,
+                      AudioStreamRegistry* stream_registry,
                       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);
 
   // |handler_| is null if we are in the process of destruction. In this case,
   // we will ignore events from |controller_|.
   EventHandler* handler_;
+  AudioStreamRegistry* const stream_registry_;
   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::WeakPtr<AudioOutputDelegate> weak_this_;
   base::WeakPtrFactory<AudioOutputDelegate> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputDelegate);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_H_