Add GetAssociatedOutputDeviceID support to pulse.

media/audio/pulse/audio_manager_pulse.cc

Index: media/audio/pulse/audio_manager_pulse.cc
diff --git a/media/audio/pulse/audio_manager_pulse.cc b/media/audio/pulse/audio_manager_pulse.cc
index 398826ae1c360a03dcaebfcfea59e8be8e592adb..ac40a299ab75464501800e423b915bc1430d7c8d 100644
--- a/media/audio/pulse/audio_manager_pulse.cc
+++ b/media/audio/pulse/audio_manager_pulse.cc
@@ -174,6 +174,25 @@ AudioInputStream* AudioManagerPulse::MakeLowLatencyInputStream(
   return MakeInputStream(params, device_id);
 }
 
+std::string AudioManagerPulse::GetAssociatedOutputDeviceID(
+    const std::string& input_device_id) {
+  DCHECK(AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  DCHECK(input_mainloop_);
+  DCHECK(input_context_);
+  if (input_device_id == AudioDeviceDescription::kDefaultDeviceId) {

[Guido Urdaneta, 2016/08/19 14:26:18]

This check is wrong. The default output device is not by definition associated
with the default input device.

The associated output device should be in the same physical device as the input
device.

+    return AudioDeviceDescription::kDefaultDeviceId;
+  }
+
+  std::string input_bus =
+      pulse::GetBusOfInput(input_device_id, input_mainloop_, input_context_);
+  if (input_bus.empty()) {
+    return "";
+  }
+  std::string s = pulse::GetOutputCorrespondingTo(input_bus, input_mainloop_,
+                                                  input_context_);
+  return s;
+}
+
 AudioParameters AudioManagerPulse::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {