Experimental: Unmute Audio During Tab Sourced Desktop Share

media/audio/virtual_audio_output_stream.h

 // Copyright (c) 2012 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_AUDIO_VIRTUAL_AUDIO_OUTPUT_STREAM_H_
 #define MEDIA_AUDIO_VIRTUAL_AUDIO_OUTPUT_STREAM_H_
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_converter.h"
+#include "media/base/audio_shifter.h"
 
 namespace media {
 
 class VirtualAudioInputStream;
 
 // VirtualAudioOutputStream attaches to a VirtualAudioInputStream when Start()
 // is called and is used as an audio source. VirtualAudioOutputStream also
 // implements an interface so it can be used as an input to AudioConverter so
 // that we can get audio frames that match the AudioParameters that
 // VirtualAudioInputStream expects.
@@ skipping 35 matching lines @@
   AfterCloseCallback after_close_cb_;
 
   AudioSourceCallback* callback_;
   double volume_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(VirtualAudioOutputStream);
 };
 
+class MEDIA_EXPORT AudioPushSink : public AudioInputStream::AudioInputCallback {
+ public:
+  virtual void Start() = 0;
+  virtual void Stop() = 0;
+  virtual void Close() = 0;
+};
+
+class MEDIA_EXPORT LoopbackSink : public AudioPushSink,
+                                  public AudioConverter::InputCallback {
+ public:
+  typedef base::Callback<void(LoopbackSink* sink)> AfterCloseCallback;
+
+  LoopbackSink(AudioParameters param,
+               VirtualAudioInputStream* target,
+               AfterCloseCallback callback);
+  ~LoopbackSink() override;
+
+  // AudioPushSink
+  void Start() override;
+  void Stop() override;
+  void Close() override;
+  void OnData(AudioInputStream* stream,
+              const AudioBus* source,
+              uint32_t hardware_delay_bytes,
+              double volume) override;
+  void OnError(AudioInputStream* stream) override;
+
+  // AudioConverter::InputCallback
+  double ProvideInput(AudioBus* audio_bus,
+                      base::TimeDelta buffer_delay) override;
+
+ private:
+  bool started_;
+  AudioParameters params_;
+  VirtualAudioInputStream* target_;
+  std::unique_ptr<AudioShifter> shifter_;
+  AfterCloseCallback after_close_callback_;
+};
+
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_VIRTUAL_AUDIO_OUTPUT_STREAM_H_