update completion extension point to use CompletionContributorFactory

pkg/analysis_server/lib/src/plugin/server_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 analysis_server.src.plugin.server_plugin;
 
 import 'package:analysis_server/plugin/analysis/analysis_domain.dart';
 import 'package:analysis_server/plugin/analysis/analyzed_files.dart';
 import 'package:analysis_server/plugin/analysis/navigation/navigation.dart';
 import 'package:analysis_server/plugin/analysis/navigation/navigation_core.dart';
@@ skipping 171 matching lines @@
    * Return a list containing all of the assist contributors that were
    * contributed.
    */
   List<AssistContributor> get assistContributors =>
       assistContributorExtensionPoint.extensions;
 
   /**
    * Return a list containing all of the completion contributors that were
    * contributed.
    */
-  List<CompletionContributor> get completionContributors =>
-      completionContributorExtensionPoint.extensions;
+  Iterable<CompletionContributor> get completionContributors =>
+      completionContributorExtensionPoint.extensions
+          .map((CompletionContributorFactory factory) => factory());
 
   /**
    * Return a list containing all of the fix contributors that were contributed.
    */
   List<FixContributor> get fixContributors =>
       fixContributorExtensionPoint.extensions;
 
   /**
    * Return a list containing all of the index contributors that were
    * contributed.
@@ skipping 159 matching lines @@
       throw new ExtensionError(
           'Extensions to $id must be an AssistContributor');
     }
   }
 
   /**
    * Validate the given extension by throwing an [ExtensionError] if it is not a
    * valid completion contributor.
    */
   void _validateCompletionContributorExtension(Object extension) {
-    if (extension is! CompletionContributor) {
+    if (extension is! CompletionContributorFactory) {
       String id = completionContributorExtensionPoint.uniqueIdentifier;
       throw new ExtensionError(
-          'Extensions to $id must be an CompletionContributor');
+          'Extensions to $id must be an CompletionContributorFactory');
     }
   }
 
   /**
    * Validate the given extension by throwing an [ExtensionError] if it is not a
    * valid domain.
    */
   void _validateDomainExtension(Object extension) {
     if (extension is! RequestHandlerFactory) {
       String id = domainExtensionPoint.uniqueIdentifier;
@@ skipping 53 matching lines @@
    * valid analysis domain receiver.
    */
   void _validateSetAnalysisDomainFunction(Object extension) {
     if (extension is! SetAnalysisDomain) {
       String id = setAnalysisDomainExtensionPoint.uniqueIdentifier;
       throw new ExtensionError(
           'Extensions to $id must be a SetAnalysisDomain function');
     }
   }
 }