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

diff --git a/google/oauth2/__init__.py b/google/oauth2/__init__.py
index 6d3ee7f..4fb71fd 100644
--- a/google/oauth2/__init__.py
+++ b/google/oauth2/__init__.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/google/oauth2/_client.py b/google/oauth2/_client.py
index 4ba31a8..4487163 100644
--- a/google/oauth2/_client.py
+++ b/google/oauth2/_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/google/oauth2/credentials.py b/google/oauth2/credentials.py
index 71d2f61..1adcbf6 100644
--- a/google/oauth2/credentials.py
+++ b/google/oauth2/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/google/oauth2/id_token.py b/google/oauth2/id_token.py
index e80c48f..5113c99 100644
--- a/google/oauth2/id_token.py
+++ b/google/oauth2/id_token.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/google/oauth2/service_account.py b/google/oauth2/service_account.py
index 17fdd51..af86588 100644
--- a/google/oauth2/service_account.py
+++ b/google/oauth2/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.