Get rid of all the library tags.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1582703002 .
diff --git a/lib/oauth2.dart b/lib/oauth2.dart
index 01474ed..3b81cf1 100644
--- a/lib/oauth2.dart
+++ b/lib/oauth2.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2;
-
 export 'src/authorization_code_grant.dart';
 export 'src/resource_owner_password_grant.dart';
 export 'src/client.dart';
diff --git a/lib/src/authorization_code_grant.dart b/lib/src/authorization_code_grant.dart
index 7a73d44..1cb45da 100644
--- a/lib/src/authorization_code_grant.dart
+++ b/lib/src/authorization_code_grant.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.authorization_code_grant;
-
 import 'dart:async';
 
 import 'package:http/http.dart' as http;
diff --git a/lib/src/authorization_exception.dart b/lib/src/authorization_exception.dart
index 838d001..9ce4b8c 100644
--- a/lib/src/authorization_exception.dart
+++ b/lib/src/authorization_exception.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.authorization_exception;
-
 /// An exception raised when OAuth2 authorization fails.
 class AuthorizationException implements Exception {
   /// The name of the error.
diff --git a/lib/src/client.dart b/lib/src/client.dart
index c27ab4e..fc74147 100644
--- a/lib/src/client.dart
+++ b/lib/src/client.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.client;
-
 import 'dart:async';
 
 import 'package:http/http.dart' as http;
diff --git a/lib/src/credentials.dart b/lib/src/credentials.dart
index 0a12f3f..49d2a64 100644
--- a/lib/src/credentials.dart
+++ b/lib/src/credentials.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.credentials;
-
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
diff --git a/lib/src/expiration_exception.dart b/lib/src/expiration_exception.dart
index f684e6a..2df2f8d 100644
--- a/lib/src/expiration_exception.dart
+++ b/lib/src/expiration_exception.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.expiration_exception;
-
 import 'credentials.dart';
 
 /// An exception raised when attempting to use expired OAuth2 credentials.
diff --git a/lib/src/handle_access_token_response.dart b/lib/src/handle_access_token_response.dart
index ef9b198..94d9487 100644
--- a/lib/src/handle_access_token_response.dart
+++ b/lib/src/handle_access_token_response.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.handle_access_token_response;
-
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
diff --git a/lib/src/resource_owner_password_grant.dart b/lib/src/resource_owner_password_grant.dart
index 28498ca..f67382b 100644
--- a/lib/src/resource_owner_password_grant.dart
+++ b/lib/src/resource_owner_password_grant.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.resource_owner_password_grant;
-
 import 'dart:async';
 
 import 'package:http/http.dart' as http;
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index bf260eb..e7cc550 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library oauth2.utils;
-
 import 'dart:convert';
 
 import 'package:crypto/crypto.dart';
diff --git a/test/handle_access_token_response_test.dart b/test/handle_access_token_response_test.dart
index 4d82262..fe2a338 100644
--- a/test/handle_access_token_response_test.dart
+++ b/test/handle_access_token_response_test.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library handle_access_token_response_test;
-
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;