Log audio system used to WebRTC log.

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
diff --git a/media/audio/mac/audio_manager_mac.cc b/media/audio/mac/audio_manager_mac.cc
index 14877a95f92eb8321907344a80187c9c9ae63a5f..37c9658f898c194831a4dacc5cb8eb2ed64906ee 100644
--- a/media/audio/mac/audio_manager_mac.cc
+++ b/media/audio/mac/audio_manager_mac.cc
@@ -603,6 +603,10 @@ std::string AudioManagerMac::GetAssociatedOutputDeviceID(
   return std::string();
 }
 
+const char* AudioManagerMac::GetName() {
+  return "Mac";
+}
+
 AudioOutputStream* AudioManagerMac::MakeLinearOutputStream(
     const AudioParameters& params,
     const LogCallback& log_callback) {