Let default device in PulseAudio be the system default device

media/audio/pulse/pulse_input.h

Index: media/audio/pulse/pulse_input.h
diff --git a/media/audio/pulse/pulse_input.h b/media/audio/pulse/pulse_input.h
index e0b2be9e2ef31134f7680b59e82956708844ca7f..93a4478063ba49c2043395faa977b8f2f7b7280c 100644
--- a/media/audio/pulse/pulse_input.h
+++ b/media/audio/pulse/pulse_input.h
@@ -15,6 +15,7 @@
 #include "media/audio/audio_device_name.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
+#include "media/audio/pulse/pulse_util.h"
 #include "media/base/audio_block_fifo.h"
 
 namespace media {
@@ -81,6 +82,20 @@ class PulseAudioInputStream : public AgcAudioStream<AudioInputStream> {
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PulseAudioInputStream);
+  friend void pulse::SystemDefaultInputDeviceCallback(
+      pa_context* context,
+      const pa_server_info* info,
+      void* user_data);
+  friend std::string pulse::GetSystemDefaultInputDevice(
+      pa_threaded_mainloop* mainloop,
+      pa_context* context);
+  friend void pulse::SystemDefaultOutputDeviceCallback(
+      pa_context* context,
+      const pa_server_info* info,
+      void* user_data);
+  friend std::string pulse::GetSystemDefaultOutputDevice(
+      pa_threaded_mainloop* mainloop,
+      pa_context* context);
 };
 
 }  // namespace media