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..340f88f9b197795ddcd95dbb95061bce7b41660f 100644
--- a/media/audio/pulse/audio_manager_pulse.cc
+++ b/media/audio/pulse/audio_manager_pulse.cc
@@ -174,6 +174,29 @@ AudioInputStream* AudioManagerPulse::MakeLowLatencyInputStream(
   return MakeInputStream(params, device_id);
 }
 
+std::string AudioManagerPulse::GetDefaultOutputDeviceID() {
+  return pulse::GetRealDefaultDeviceId(input_mainloop_, input_context_,
+                                       pulse::RequestType::OUTPUT);
+}
+
+std::string AudioManagerPulse::GetAssociatedOutputDeviceID(
+    const std::string& input_device_id) {
+  DCHECK(AudioManager::Get()->GetTaskRunner()->BelongsToCurrentThread());
+  DCHECK(input_mainloop_);
+  DCHECK(input_context_);
+  std::string input =
+      (input_device_id == AudioDeviceDescription::kDefaultDeviceId)
+          ? pulse::GetRealDefaultDeviceId(input_mainloop_, input_context_,
+                                          pulse::RequestType::INPUT)
+          : input_device_id;
+
+  std::string input_bus =
+      pulse::GetBusOfInput(input_mainloop_, input_context_, input);
+  return input_bus.empty() ? ""
+                           : pulse::GetOutputCorrespondingTo(
+                                 input_mainloop_, input_context_, input_bus);
+}
+
 AudioParameters AudioManagerPulse::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {