Add AudioManager::GetAudioOutputDeviceNames and implement for pulseaudio.

media/audio/pulse/audio_manager_pulse.h

Index: media/audio/pulse/audio_manager_pulse.h
diff --git a/media/audio/pulse/audio_manager_pulse.h b/media/audio/pulse/audio_manager_pulse.h
index f46f2bef66d86f16207e99e199cfeebb3ba8cb86..8fc4310cba3fa680549b6e6ea2d1d80901bd99b1 100644
--- a/media/audio/pulse/audio_manager_pulse.h
+++ b/media/audio/pulse/audio_manager_pulse.h
@@ -27,6 +27,8 @@ class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
   virtual void ShowAudioInputSettings() OVERRIDE;
   virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names)
       OVERRIDE;
+  virtual void GetAudioOutputDeviceNames(media::AudioDeviceNames* device_names)
+      OVERRIDE;
   virtual AudioParameters GetInputStreamParameters(
       const std::string& device_id) OVERRIDE;
 
@@ -51,6 +53,8 @@ class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
   bool Init();
   void DestroyPulse();
 
+  void GetAudioDeviceNames(bool input, media::AudioDeviceNames* device_names);
+
   // Callback to get the devices' info like names, used by GetInputDevices().
   static void InputDevicesInfoCallback(pa_context* context,
                                        const pa_source_info* info,