Make client use binder interface on brillo

TEST=Verified status and update commands
Bug: 25908638

Change-Id: I7994de41001b4e116bffa539f23f1344ab1deae9
diff --git a/client_library/client_dbus.h b/client_library/client_dbus.h
index 3590a21..e6bbe36 100644
--- a/client_library/client_dbus.h
+++ b/client_library/client_dbus.h
@@ -69,7 +69,7 @@
 
   bool GetChannel(std::string* out_channel) const override;
 
-  void RegisterStatusUpdateHandler(StatusUpdateHandler* handler) override;
+  bool RegisterStatusUpdateHandler(StatusUpdateHandler* handler) override;
 
  private:
   std::unique_ptr<org::chromium::UpdateEngineInterfaceProxy> proxy_;