Avoid InterfaceImpl in //services/test_service

R=viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/924543003
diff --git a/services/test_service/test_service_impl.cc b/services/test_service/test_service_impl.cc
index 1a9cae39..21cab52 100644
--- a/services/test_service/test_service_impl.cc
+++ b/services/test_service/test_service_impl.cc
@@ -16,8 +16,12 @@
 namespace test {
 
 TestServiceImpl::TestServiceImpl(ApplicationImpl* app_impl,
-                                 TestServiceApplication* application)
-    : application_(application), app_impl_(app_impl) {
+                                 TestServiceApplication* application,
+                                 InterfaceRequest<TestService> request)
+    : application_(application),
+      app_impl_(app_impl),
+      binding_(this, request.Pass()) {
+  binding_.set_error_handler(this);
 }
 
 TestServiceImpl::~TestServiceImpl() {