Replace try/finally with PerformanceTag.makeCurrentWhile().

pkg/analysis_server/lib/src/channel/byte_stream_channel.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 channel.byte_stream;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/channel/channel.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
-import 'package:analyzer/src/generated/utilities_general.dart';
 
 /**
  * Instances of the class [ByteStreamClientChannel] implement a
  * [ClientCommunicationChannel] that uses a stream and a sink (typically,
  * standard input and standard output) to communicate with servers.
  */
 class ByteStreamClientChannel implements ClientCommunicationChannel {
   final Stream input;
   final IOSink output;
 
@@ skipping 89 matching lines @@
     });
   }
 
   @override
   void sendNotification(Notification notification) {
     // Don't send any further notifications after the communication channel is
     // closed.
     if (_closeRequested) {
       return;
     }
-    PerformanceTag prevTag =
-        ServerPerformanceStatistics.serverChannel.makeCurrent();
-    try {
+    ServerPerformanceStatistics.serverChannel.makeCurrentWhile(() {
       String jsonEncoding = JSON.encode(notification.toJson());
       _outputLine(jsonEncoding);
       _instrumentationService.logNotification(jsonEncoding);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 
   @override
   void sendResponse(Response response) {
     // Don't send any further responses after the communication channel is
     // closed.
     if (_closeRequested) {
       return;
     }
-    PerformanceTag prevTag =
-        ServerPerformanceStatistics.serverChannel.makeCurrent();
-    try {
+    ServerPerformanceStatistics.serverChannel.makeCurrentWhile(() {
       String jsonEncoding = JSON.encode(response.toJson());
       _outputLine(jsonEncoding);
       _instrumentationService.logResponse(jsonEncoding);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 
   /**
    * Send the string [s] to [_output] followed by a newline.
    */
   void _outputLine(String s) {
     _output.writeln(s);
   }
 
   /**
    * Read a request from the given [data] and use the given function to handle
    * the request.
    */
   void _readRequest(Object data, void onRequest(Request request)) {
     // Ignore any further requests after the communication channel is closed.
     if (_closed.isCompleted) {
       return;
     }
-    PerformanceTag prevTag =
-        ServerPerformanceStatistics.serverChannel.makeCurrent();
-    try {
+    ServerPerformanceStatistics.serverChannel.makeCurrentWhile(() {
       _instrumentationService.logRequest(data);
       // Parse the string as a JSON descriptor and process the resulting
       // structure as a request.
       Request request = new Request.fromString(data);
       if (request == null) {
         sendResponse(new Response.invalidRequestFormat());
         return;
       }
       onRequest(request);
-    } finally {
-      prevTag.makeCurrent();
-    }
+    });
   }
 }