Make more use of generated classes in analysis server.

pkg/analysis_server/lib/src/domain_completion.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 domain.completion;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_server/src/protocol2.dart' show
+    CompletionGetSuggestionsParams;
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/completion_suggestion.dart';
 
 /**
  * Instances of the class [CompletionDomainHandler] implement a [RequestHandler]
  * that handles requests in the search domain.
  */
 class CompletionDomainHandler implements RequestHandler {
   /**
    * The analysis server that is using this handler to process requests.
@@ skipping 20 matching lines @@
     } on RequestFailure catch (exception) {
       return exception.response;
     }
     return null;
   }
 
   /**
    * Process a `completion.getSuggestions` request.
    */
   Response processRequest(Request request) {
-    // extract param
-    String file = request.getRequiredParameter(FILE).asString();
-    int offset = request.getRequiredParameter(OFFSET).asInt();
+    // extract params
+    var params = new CompletionGetSuggestionsParams.fromRequest(request);
     // schedule completion analysis
     String completionId = (_nextCompletionId++).toString();
     CompletionManager.create(
-        server.getAnalysisContext(file),
-        server.getSource(file),
-        offset,
+        server.getAnalysisContext(params.file),
+        server.getSource(params.file),
+        params.offset,
         server.searchEngine).results().listen((CompletionResult result) {
       sendCompletionNotification(
           completionId,
           result.replacementOffset,
           result.replacementLength,
           result.suggestions,
           result.last);
     });
     // initial response without results
     return new Response(request.id)..setResult(ID, completionId);
   }
 
   /**
    * Send completion notification results.
    */
   void sendCompletionNotification(String completionId, int replacementOffset,
       int replacementLength, Iterable<CompletionSuggestion> results, bool isLast) {
     Notification notification = new Notification(COMPLETION_RESULTS);
     notification.setParameter(ID, completionId);
     notification.setParameter(REPLACEMENT_OFFSET, replacementOffset);
     notification.setParameter(REPLACEMENT_LENGTH, replacementLength);
     notification.setParameter(RESULTS, results);
     notification.setParameter(LAST, isLast);
     server.sendNotification(notification);
   }
 }