Move the wire protocol support into the public API

pkg/analysis_server/lib/plugin/analysis/analysis_domain.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.
 
 /**
  * Support for client code that interacts with the analysis domain of an
  * analysis server.
  *
  * Plugins can gain access to the request handler that implements the analysis
  * domain in order to extend the functionality of that domain. The class
@@ skipping 11 matching lines @@
  *       registerExtension(
  *           SET_ANALYSIS_DOMAIN_EXTENSION_POINT_ID,
  *           (AnalysisDomain domain) => analysisDomain = domain);
  *       ...
  *     }
  */
 library analysis_server.plugin.analysis.analysis_domain;
 
 import 'dart:async';
 
+import 'package:analysis_server/plugin/protocol/protocol.dart'
+    show AnalysisService;
 import 'package:analysis_server/src/plugin/server_plugin.dart';
-import 'package:analysis_server/src/protocol.dart' show AnalysisService;
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, ComputedResult;
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:analyzer/task/model.dart' show ResultDescriptor;
 import 'package:plugin/plugin.dart';
 
 /**
  * The identifier of the extension point that allows plugins to get access to an
  * [AnalysisDomain]. The object used as an extension must be a
  * [SetAnalysisDomain].
@@ skipping 26 matching lines @@
    */
   Stream<ComputedResult> onResultComputed(ResultDescriptor result);
 
   /**
    * Schedule sending the given [service] notifications for the given [source]
    * in the given [context].
    */
   void scheduleNotification(
       AnalysisContext context, Source source, AnalysisService service);
 }