Deprecate WebSocketChannel.

lib/src/web_socket/compatible.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.
 
 import 'dart:async';
 
 import 'package:crypto/crypto.dart';
 
 import '../copy/web_socket_impl.dart';
-import 'channel.dart';
 
-/// Use [WebSocketChannel] instead.
+/// This class is deprecated.
+///
+/// Use the [`web_socket_channel`][web_socket_channel] package instead.
+///
+/// [web_socket_channel]: https://pub.dartlang.org/packages/web_socket_channel
 @Deprecated("Will be removed in 3.0.0.")
 abstract class CompatibleWebSocket implements Stream, StreamSink {
   /// The interval for sending ping signals.
   ///
   /// If a ping message is not answered by a pong message from the peer, the
   /// `WebSocket` is assumed disconnected and the connection is closed with a
   /// [WebSocketStatus.GOING_AWAY] close code. When a ping signal is sent, the
   /// pong message must be received within [pingInterval].
   ///
   /// There are never two outstanding pings at any given time, and the next ping
@@ skipping 63 matching lines @@
   /// Closes the web socket connection.
   ///
   /// [closeCode] and [closeReason] are the [close code][] and [reason][] sent
   /// to the remote peer, respectively. If they are omitted, the peer will see
   /// a "no status received" code with no reason.
   ///
   /// [close code]: https://tools.ietf.org/html/rfc6455#section-7.1.5
   /// [reason]: https://tools.ietf.org/html/rfc6455#section-7.1.6
   Future close([int closeCode, String closeReason]);
 }