Analysis server context ID is now specified by the client.

pkg/analysis_server/lib/src/protocol.dart

 // Copyright (c) 2014, 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 protocol;
 
 import 'dart:convert' show JsonDecoder;
 
 /**
  * Instances of the class [Request] represent a request that was received.
@@ skipping 247 matching lines @@
   Response.unknownAnalysisOption(Request request, String optionName)
     : this(request.id, new RequestError(-6, 'Unknown analysis option: "$optionName"'));
 
   /**
    * Initialize a newly created instance to represent an error condition caused
    * by a [request] that cannot be handled by any known handlers.
    */
   Response.unknownRequest(Request request)
     : this(request.id, new RequestError(-7, 'Unknown request'));
 
+  Response.contextAlreadyExists(Request request)
+    : this(request.id, new RequestError(-8, 'Context already exists'));
+
   /**
    * Initialize a newly created instance based upon the given JSON data
    */
   factory Response.fromJson(Map<String, Object> json) {
     try {
       var id = json[Response.ID];
       if (id is! String) {
         return null;
       }
       var error = json[Response.ERROR];
@@ skipping 319 matching lines @@
   /**
    * The response to be returned as a result of the failure.
    */
   final Response response;
 
   /**
    * Initialize a newly created exception to return the given reponse.
    */
   RequestFailure(this.response);
 }