docs(copyright): correct name of company for commits after 2015 (#440)

diff --git a/tests/oauth2/test__client.py b/tests/oauth2/test__client.py
index 052390a..c3ae2af 100644
--- a/tests/oauth2/test__client.py
+++ b/tests/oauth2/test__client.py
@@ -1,4 +1,4 @@
-# Copyright 2016 Google Inc.
+# Copyright 2016 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/tests/oauth2/test_credentials.py b/tests/oauth2/test_credentials.py
index af10f2f..bdb63e9 100644
--- a/tests/oauth2/test_credentials.py
+++ b/tests/oauth2/test_credentials.py
@@ -1,4 +1,4 @@
-# Copyright 2016 Google Inc.
+# Copyright 2016 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/tests/oauth2/test_service_account.py b/tests/oauth2/test_service_account.py
index 0f9d460..897374a 100644
--- a/tests/oauth2/test_service_account.py
+++ b/tests/oauth2/test_service_account.py
@@ -1,4 +1,4 @@
-# Copyright 2016 Google Inc.
+# Copyright 2016 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.