Swap target, request for request, target in secure_authorized_channel's argument order. (#81)


diff --git a/system_tests/test_grpc.py b/system_tests/test_grpc.py
index 0db9f1d..7d436c5 100644
--- a/system_tests/test_grpc.py
+++ b/system_tests/test_grpc.py
@@ -28,7 +28,7 @@
         publisher_api.PublisherApi.DEFAULT_SERVICE_PORT)
 
     channel = google.auth.transport.grpc.secure_authorized_channel(
-        credentials, target, http_request)
+        credentials, http_request, target)
 
     # Create a pub/sub client.
     client = publisher_api.PublisherApi(channel=channel)