Adds PID to `server.connected` notification (#26744).

pkg/analysis_server/lib/src/analysis_server.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 analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:core' hide Resource;
+import 'dart:io' as io;
 import 'dart:math' show max;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart'
     hide AnalysisOptions, Element;
 import 'package:analysis_server/src/analysis_logger.dart';
 import 'package:analysis_server/src/channel/channel.dart';
 import 'package:analysis_server/src/context_manager.dart';
 import 'package:analysis_server/src/operation/operation.dart';
 import 'package:analysis_server/src/operation/operation_analysis.dart';
 import 'package:analysis_server/src/operation/operation_queue.dart';
@@ skipping 337 matching lines @@
     _onPriorityChangeController =
         new StreamController<PriorityChangeEvent>.broadcast();
     running = true;
     onAnalysisStarted.first.then((_) {
       onAnalysisComplete.then((_) {
         performanceAfterStartup = new ServerPerformance();
         _performance = performanceAfterStartup;
       });
     });
     _setupIndexInvalidation();
+    String pid = io.pid.toString();
     Notification notification =
-        new ServerConnectedParams(VERSION).toNotification();
+        new ServerConnectedParams(VERSION, pid).toNotification();
     channel.sendNotification(notification);
     channel.listen(handleRequest, onDone: done, onError: error);
     handlers = serverPlugin.createDomains(this);
   }
 
   /**
    * Return the [AnalysisContext]s that are being used to analyze the analysis
    * roots.
    */
   Iterable<AnalysisContext> get analysisContexts =>
@@ skipping 1371 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }