Let default device in PulseAudio be the system default device

media/audio/pulse/pulse_input.cc

Index: media/audio/pulse/pulse_input.cc
diff --git a/media/audio/pulse/pulse_input.cc b/media/audio/pulse/pulse_input.cc
index 8d4aeea2079d201a69e52fb48e4344680c467d70..627367eea38bafbf65dd2d594fbc102eff2c3c30 100644
--- a/media/audio/pulse/pulse_input.cc
+++ b/media/audio/pulse/pulse_input.cc
@@ -48,11 +48,39 @@ PulseAudioInputStream::~PulseAudioInputStream() {
   DCHECK(!handle_);
 }
 
+// static, used by pa_context_get_server_info.
+void PulseAudioInputStream::GetSystemDefaultInputDeviceCallback(
+    pa_context* context,
+    const pa_server_info* info,
+    void* user_data) {
+  PulseAudioInputStream* stream =
+      reinterpret_cast<PulseAudioInputStream*>(user_data);
+  stream->default_system_device_name_ = info->default_source_name;

[Henrik Grunell, 2016/03/09 00:49:17]

Add setter function for |default_system_device_name_| and getter for
|pa_mainloop_|.

[rchtara, 2016/03/09 16:16:09]

Done.

+  pa_threaded_mainloop* pa_mainloop =
+      static_cast<pa_threaded_mainloop*>(stream->pa_mainloop_);

[Henrik Grunell, 2016/03/09 00:49:17]

It doesn't look like casting is needed here.

[rchtara, 2016/03/09 16:16:09]

Done.

+  pa_threaded_mainloop_signal(pa_mainloop, 0);
+}
+
+void PulseAudioInputStream::GetSystemDefaultInputDevice() {
+  DCHECK(pa_mainloop_);
+  DCHECK(pa_context_);
+  pa_operation* operation = pa_context_get_server_info(
+      pa_context_, PulseAudioInputStream::GetSystemDefaultInputDeviceCallback,
+      this);
+  WaitForOperationCompletion(pa_mainloop_, operation);
+}
+
 bool PulseAudioInputStream::Open() {
   DCHECK(thread_checker_.CalledOnValidThread());
   AutoPulseLock auto_lock(pa_mainloop_);
+  std::string device_to_use_ = device_name_;

[Henrik Grunell, 2016/03/09 00:49:17]

"device_to_use_" -> "device_name_to_use". (No trailing "_".)

[rchtara, 2016/03/09 16:16:09]

Done.

+  if (device_name_ == AudioManagerBase::kDefaultDeviceId) {
+    GetSystemDefaultInputDevice();
+    device_to_use_ = default_system_device_name_;
+  }
+
   if (!pulse::CreateInputStream(pa_mainloop_, pa_context_, &handle_, params_,
-                                device_name_, &StreamNotifyCallback, this)) {
+                                device_to_use_, &StreamNotifyCallback, this)) {
     return false;
   }