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

dbus/signal_sender_verification_unittest.cc

Index: dbus/signal_sender_verification_unittest.cc
diff --git a/dbus/signal_sender_verification_unittest.cc b/dbus/signal_sender_verification_unittest.cc
index cbf4b5f71921b5dae830f358e8d7d7450f64b42b..1d8f6e1d64ebccec446059109a9e67346e3c900c 100644
--- a/dbus/signal_sender_verification_unittest.cc
+++ b/dbus/signal_sender_verification_unittest.cc
@@ -120,12 +120,9 @@ class SignalSenderVerificationTest : public testing::Test {
     message_loop_.Quit();
   }
 
-  void OnNameOwnerChanged(bool* called_flag, Signal* signal) {
-    MessageReader reader(signal);
-    std::string name, old_owner, new_owner;
-    ASSERT_TRUE(reader.PopString(&name));
-    ASSERT_TRUE(reader.PopString(&old_owner));
-    ASSERT_TRUE(reader.PopString(&new_owner));
+  void OnNameOwnerChanged(bool* called_flag,
+                          const std::string& old_owner,
+                          const std::string& new_owner) {
     latest_name_owner_ = new_owner;
     *called_flag = true;
     message_loop_.Quit();