Clean up package imports and library names

pkg/analyzer/lib/src/plugin/options_plugin.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // 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 analyzer.src.plugin.options;
+library analyzer.src.plugin.options_plugin;
 
 import 'package:analyzer/plugin/options.dart';
 import 'package:analyzer/plugin/task.dart';
 import 'package:analyzer/src/task/options.dart';
 import 'package:plugin/plugin.dart';
 
 /// A plugin that defines the extension points and extensions that are defined
 /// by applications that want to consume options defined in the analysis
 /// options file.
 class OptionsPlugin implements Plugin {
@@ skipping 56 matching lines @@
 
   /// Validate the given extension by throwing an [ExtensionError] if it is not
   /// a valid options validator.
   void _validateOptionsValidatorExtension(Object extension) {
     if (extension is! OptionsValidator) {
       String id = optionsValidatorExtensionPoint.uniqueIdentifier;
       throw new ExtensionError('Extensions to $id must be an OptionsValidator');
     }
   }
 }