MediaStream audio: Refactor 3 separate "glue" implementations into one.

content/renderer/media/webrtc/webrtc_audio_sink.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
+// 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_RENDERER_MEDIA_WEBRTC_WEBRTC_LOCAL_AUDIO_TRACK_ADAPTER_H_
-#define CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_LOCAL_AUDIO_TRACK_ADAPTER_H_
+#ifndef CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_AUDIO_SINK_H_
+#define CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_AUDIO_SINK_H_
 
+#include <stdint.h>
+
+#include <memory>
 #include <vector>
 
+#include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/scoped_vector.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
+#include "content/public/renderer/media_stream_audio_sink.h"
 #include "content/renderer/media/media_stream_audio_level_calculator.h"
 #include "content/renderer/media/media_stream_audio_processor.h"
+#include "media/base/audio_parameters.h"
+#include "media/base/audio_push_fifo.h"
 #include "third_party/webrtc/api/mediastreamtrack.h"
 #include "third_party/webrtc/media/base/audiorenderer.h"
 
-namespace cricket {
-class AudioRenderer;
-}
-
-namespace webrtc {
-class AudioSourceInterface;
-class AudioProcessorInterface;
-}
-
 namespace content {
 
-class MediaStreamAudioProcessor;
-class WebRtcAudioSinkAdapter;
-class WebRtcLocalAudioTrack;
-
-// Provides an implementation of the webrtc::AudioTrackInterface that can be
-// bound/unbound to/from a MediaStreamAudioTrack.  In other words, this is an
-// adapter that sits between the media stream object graph and WebRtc's object
-// graph and proxies between the two.
-class CONTENT_EXPORT WebRtcLocalAudioTrackAdapter
-    : NON_EXPORTED_BASE(
-          public webrtc::MediaStreamTrack<webrtc::AudioTrackInterface>) {
+// Provides an implementation of the MediaStreamAudioSink which re-chunks audio
+// data into the 10ms chunks required by WebRTC and then delivers the audio to
+// one or more objects implementing the webrtc::AudioTrackSinkInterface.
+//
+// The inner class, Adapter, implements the webrtc::AudioTrackInterface and
+// manages one or more "WebRTC sinks" (i.e., instances of
+// webrtc::AudioTrackSinkInterface) which are added/removed on the WebRTC
+// signaling thread.
+class CONTENT_EXPORT WebRtcAudioSink : public MediaStreamAudioSink {
  public:
-  static scoped_refptr<WebRtcLocalAudioTrackAdapter> Create(
+  WebRtcAudioSink(
       const std::string& label,
-      webrtc::AudioSourceInterface* track_source);
-
-  WebRtcLocalAudioTrackAdapter(
-      const std::string& label,
-      webrtc::AudioSourceInterface* track_source,
+      scoped_refptr<webrtc::AudioSourceInterface> track_source,
       scoped_refptr<base::SingleThreadTaskRunner> signaling_task_runner);
 
-  ~WebRtcLocalAudioTrackAdapter() override;
+  ~WebRtcAudioSink() override;
 
-  void Initialize(WebRtcLocalAudioTrack* owner);
+  webrtc::AudioTrackInterface* webrtc_audio_track() const {
+    return adapter_.get();
+  }
 
   // Set the object that provides shared access to the current audio signal
-  // level.  This method may only be called once, before the audio data flow
-  // starts, and before any calls to GetSignalLevel() might be made.
+  // level. This is passed via the Adapter to libjingle. This method may only
+  // be called once, before the audio data flow starts, and before any calls to
+  // Adapter::GetSignalLevel() might be made.
   void SetLevel(scoped_refptr<MediaStreamAudioLevelCalculator::Level> level);
 
-  // Method called by the WebRtcLocalAudioTrack to set the processor that
-  // applies signal processing on the data of the track.
-  // This class will keep a reference of the |processor|.
-  // Called on the main render thread.
-  // This method may only be called once, before the audio data flow starts, and
-  // before any calls to GetAudioProcessor() might be made.
+  // Set the processor that applies signal processing on the data from the
+  // source. This is passed via the Adapter to libjingle. This method may only
+  // be called once, before the audio data flow starts, and before any calls to
+  // GetAudioProcessor() might be made.
   void SetAudioProcessor(scoped_refptr<MediaStreamAudioProcessor> processor);
 
-  // webrtc::MediaStreamTrack implementation.
-  std::string kind() const override;
-  bool set_enabled(bool enable) override;
+  // MediaStreamSink override.
+  void OnEnabledChanged(bool enabled) override;
 
  private:
-  // webrtc::AudioTrackInterface implementation.
-  void AddSink(webrtc::AudioTrackSinkInterface* sink) override;
-  void RemoveSink(webrtc::AudioTrackSinkInterface* sink) override;
-  bool GetSignalLevel(int* level) override;
-  rtc::scoped_refptr<webrtc::AudioProcessorInterface> GetAudioProcessor()
-      override;
-  webrtc::AudioSourceInterface* GetSource() const override;
+  // Private implementation of the webrtc::AudioTrackInterface whose control
+  // methods are all called on the WebRTC signaling thread. This class is
+  // ref-counted, per the requirements of webrtc::AudioTrackInterface.
+  class Adapter
+      : NON_EXPORTED_BASE(
+            public webrtc::MediaStreamTrack<webrtc::AudioTrackInterface>) {
+   public:
+    Adapter(const std::string& label,
+            scoped_refptr<webrtc::AudioSourceInterface> source,
+            scoped_refptr<base::SingleThreadTaskRunner> signaling_task_runner);
 
-  // Weak reference.
-  WebRtcLocalAudioTrack* owner_;
+    base::SingleThreadTaskRunner* signaling_task_runner() const {
+      return signaling_task_runner_.get();
+    }
 
-  // The source of the audio track which handles the audio constraints.
-  // TODO(xians): merge |track_source_| to |capturer_| in WebRtcLocalAudioTrack.
-  rtc::scoped_refptr<webrtc::AudioSourceInterface> track_source_;
+    // These setters are called before the audio data flow starts, and before
+    // any methods called on the signaling thread reference these objects.
+    void set_processor(scoped_refptr<MediaStreamAudioProcessor> processor) {
+      audio_processor_ = std::move(processor);
+    }
+    void set_level(
+        scoped_refptr<MediaStreamAudioLevelCalculator::Level> level) {
+      level_ = std::move(level);
+    }
 
-  // Libjingle's signaling thread.
-  const scoped_refptr<base::SingleThreadTaskRunner> signaling_task_runner_;
+    // Delivers a 10ms chunk of audio to all WebRTC sinks managed by this
+    // Adapter. This is called on the audio thread.
+    void DeliverPCMToWebRtcSinks(const int16_t* audio_data,
+                                 int sample_rate,
+                                 size_t number_of_channels,
+                                 size_t number_of_frames);
 
-  // The audio processsor that applies audio processing on the data of audio
-  // track.  This must be set before calls to GetAudioProcessor() are made.
-  scoped_refptr<MediaStreamAudioProcessor> audio_processor_;
+    // webrtc::MediaStreamTrack implementation.
+    std::string kind() const override;
+    bool set_enabled(bool enable) override;
 
-  // A vector of the peer connection sink adapters which receive the audio data
-  // from the audio track.
-  ScopedVector<WebRtcAudioSinkAdapter> sink_adapters_;
+    // webrtc::AudioTrackInterface implementation.
+    void AddSink(webrtc::AudioTrackSinkInterface* sink) override;
+    void RemoveSink(webrtc::AudioTrackSinkInterface* sink) override;
+    bool GetSignalLevel(int* level) override;
+    rtc::scoped_refptr<webrtc::AudioProcessorInterface> GetAudioProcessor()
+        override;
+    webrtc::AudioSourceInterface* GetSource() const override;
 
-  // Thread-safe accessor to current audio signal level.  This must be set
-  // before calls to GetSignalLevel() are made.
-  scoped_refptr<MediaStreamAudioLevelCalculator::Level> level_;
+   protected:
+    ~Adapter() override;
+
+   private:
+    const scoped_refptr<webrtc::AudioSourceInterface> source_;
+
+    // Task runner for operations that must be done on libjingle's signaling
+    // thread.
+    const scoped_refptr<base::SingleThreadTaskRunner> signaling_task_runner_;
+
+    // The audio processsor that applies audio post-processing on the source
+    // audio. This is null if there is no audio processing taking place
+    // upstream. This must be set before calls to GetAudioProcessor() are made.
+    scoped_refptr<MediaStreamAudioProcessor> audio_processor_;
+
+    // Thread-safe accessor to current audio signal level. This may be null, if
+    // not applicable to the current use case. This must be set before calls to
+    // GetSignalLevel() are made.
+    scoped_refptr<MediaStreamAudioLevelCalculator::Level> level_;
+
+    // Lock that protects concurrent access to the |sinks_| list.
+    base::Lock lock_;
+
+    // A vector of pointers to unowned WebRTC-internal objects which each
+    // receive the audio data.
+    std::vector<webrtc::AudioTrackSinkInterface*> sinks_;
+
+    DISALLOW_COPY_AND_ASSIGN(Adapter);
+  };
+
+  // MediaStreamAudioSink implementation.
+  void OnData(const media::AudioBus& audio_bus,
+              base::TimeTicks estimated_capture_time) override;
+  void OnSetFormat(const media::AudioParameters& params) override;
+
+  // Called by AudioPushFifo zero or more times during the call to OnData().
+  // Delivers audio data with the required 10ms buffer size to |adapter_|.
+  void DeliverRebufferedAudio(const media::AudioBus& audio_bus,
+                              int frame_delay);
+
+  // Owner of the WebRTC sinks. May outlive this WebRtcAudioSink (if references
+  // are held by libjingle).
+  const scoped_refptr<Adapter> adapter_;
+
+  // The current format of the audio passing through this sink.
+  media::AudioParameters params_;
+
+  // Light-weight fifo used for re-chunking audio into the 10ms chunks required
+  // by the WebRTC sinks.
+  media::AudioPushFifo fifo_;
+
+  // Buffer used for converting into the required signed 16-bit integer
+  // interleaved samples.
+  std::unique_ptr<int16_t[]> interleaved_data_;
+
+  // In debug builds, check that WebRtcAudioSink's public methods are all being
+  // called on the main render thread.
+  base::ThreadChecker thread_checker_;
+
+  // Used to DCHECK that OnSetFormat() and OnData() are called on the same
+  // thread.
+  base::ThreadChecker audio_thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebRtcAudioSink);
 };
 
 }  // namespace content
 
-#endif  // CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_LOCAL_AUDIO_TRACK_ADAPTER_H_
+#endif  // CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_AUDIO_SINK_H_