dbus: Stop accessing ObjectProxy::name_owner_changed_callback_ on the D-Bus thread

chromeos/dbus/cras_audio_client.cc

Index: chromeos/dbus/cras_audio_client.cc
diff --git a/chromeos/dbus/cras_audio_client.cc b/chromeos/dbus/cras_audio_client.cc
index 9fe839423b49bac61ca05cb1142b76a6fb3a26db..60443a2d47af3be4c65f429883c06c265b05d676 100644
--- a/chromeos/dbus/cras_audio_client.cc
+++ b/chromeos/dbus/cras_audio_client.cc
@@ -197,7 +197,8 @@ class CrasAudioClientImpl : public CrasAudioClient {
         << "Failed to connect to cras signal:" << signal_name;
   }
 
-  void NameOwnerChangedReceived(dbus::Signal* signal) {
+  void NameOwnerChangedReceived(const std::string& old_owner,
+                                const std::string& new_owner) {
     FOR_EACH_OBSERVER(Observer, observers_, AudioClientRestarted());
   }