Let default device in PulseAudio be the system default device

media/audio/pulse/pulse_input.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_PULSE_PULSE_INPUT_H_
 #define MEDIA_AUDIO_PULSE_PULSE_INPUT_H_
 
 #include <pulse/pulseaudio.h>
 #include <stddef.h>
 #include <string>
@@ skipping 23 matching lines @@
   // Implementation of AudioInputStream.
   bool Open() override;
   void Start(AudioInputCallback* callback) override;
   void Stop() override;
   void Close() override;
   double GetMaxVolume() override;
   void SetVolume(double volume) override;
   double GetVolume() override;
   bool IsMuted() override;
 
+  pa_threaded_mainloop* GetPAMainloop();
+  void SetDefaultSystemDeviceName(const std::string& name);
+
  private:
   // PulseAudio Callbacks.
   static void ReadCallback(pa_stream* handle, size_t length, void* user_data);
   static void StreamNotifyCallback(pa_stream* stream, void* user_data);
   static void VolumeCallback(pa_context* context, const pa_source_info* info,
                              int error, void* user_data);
   static void MuteCallback(pa_context* context,
                            const pa_source_info* info,
                            int error,
                            void* user_data);
 
+  // Get default system input device for the input stream.
+  void GetSystemDefaultInputDevice();
+
   // Helper for the ReadCallback.
   void ReadData();
 
   // Utility method used by GetVolume() and IsMuted().
   bool GetSourceInformation(pa_source_info_cb_t callback);
 
   AudioManagerPulse* audio_manager_;
   AudioInputCallback* callback_;
-  std::string device_name_;
+  const std::string device_name_;
+  // The name of the system default device. Set by
+  // GetSystemDefaultInputDeviceCallback if |device_name_| is set to be the
+  // default device.
+  std::string default_system_device_name_;
+
   AudioParameters params_;
   int channels_;
   double volume_;
   bool stream_started_;
 
   // Set to true in IsMuted() if user has muted the selected microphone in the
   // sound settings UI.
   bool muted_;
 
   // Holds the data from the OS.
   AudioBlockFifo fifo_;
 
   // PulseAudio API structs.
   pa_threaded_mainloop* pa_mainloop_; // Weak.
   pa_context* pa_context_;  // Weak.
   pa_stream* handle_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PulseAudioInputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_PULSE_PULSE_INPUT_H_