Use shelf in pub's barback and admin servers.

sdk/lib/_internal/pub/lib/src/barback/admin_server.dart

Index: sdk/lib/_internal/pub/lib/src/barback/admin_server.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/admin_server.dart b/sdk/lib/_internal/pub/lib/src/barback/admin_server.dart
index f31d4d2ceb9959eee2f93931de2f51dcb5c637a1..80603b1b22049e9cd8ac96562c9bfe3fc90c6bbd 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/admin_server.dart
+++ b/sdk/lib/_internal/pub/lib/src/barback/admin_server.dart
@@ -7,6 +7,9 @@ library pub.barback.admin_server;
 import 'dart:async';
 import 'dart:io';
 
+import 'package:http_parser/http_parser.dart';
+import 'package:shelf/shelf.dart' as shelf;
+import 'package:shelf_web_socket/shelf_web_socket.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import '../log.dart' as log;
@@ -19,7 +22,9 @@ import 'web_socket_api.dart';
 // See #16954.
 class AdminServer extends BaseServer {
   /// All currently open [WebSocket] connections.
-  final _webSockets = new Set<WebSocket>();
+  final _webSockets = new Set<CompatibleWebSocket>();
+
+  shelf.Handler _handler;
 
   /// Creates a new server and binds it to [port] of [host].
   static Future<AdminServer> bind(AssetEnvironment environment,
@@ -31,7 +36,11 @@ class AdminServer extends BaseServer {
   }
 
   AdminServer._(AssetEnvironment environment, HttpServer server)
-      : super(environment, server);
+      : super(environment, server) {
+    _handler = new shelf.Cascade()
+        .add(webSocketHandler(_handleWebSocket))
+        .add(_handleHttp).handler;
+  }
 
   /// Closes the server and all Web Socket connections.
   Future close() {
@@ -40,33 +49,23 @@ class AdminServer extends BaseServer {
     return Future.wait(futures);
   }
 
-  /// Handles an HTTP request.
-  void handleRequest(HttpRequest request) {
-    if (WebSocketTransformer.isUpgradeRequest(request)) {
-      _handleWebSocket(request);
-      return;
-    }
+  handleRequest(shelf.Request request) => _handler(request);
 
+  /// Handles an HTTP request.
+  _handleHttp(shelf.Request request) {
     // TODO(rnystrom): Actually respond to requests once there is an admin
     // interface. See #16954.
     logRequest(request, "501 Not Implemented");
-    request.response.headers.contentType =
-        ContentType.parse("text/plain; charset=utf-8");
-
-    request.response.statusCode = 501;
-    request.response.reasonPhrase = "Not Implemented";
-    request.response.write(
-        "Currently this server only accepts Web Socket connections.");
-    request.response.close();
+    return new shelf.Response(501,
+        body: "Currently this server only accepts Web Socket connections.");
   }
 
   /// Creates a web socket for [request] which should be an upgrade request.
-  void _handleWebSocket(HttpRequest request) {
-    Chain.track(WebSocketTransformer.upgrade(request)).then((socket) {
-      _webSockets.add(socket);
-      var api = new WebSocketApi(socket, environment);
-
-      return api.listen().whenComplete(() => _webSockets.remove(api));
-    }).catchError(addError);
+  void _handleWebSocket(CompatibleWebSocket socket) {
+    _webSockets.add(socket);
+    var api = new WebSocketApi(socket, environment);
+    api.listen()
+        .whenComplete(() => _webSockets.remove(api))
+        .catchError(addError);
   }
 }