Refactor based on input on pull request.

src/Discord.Net.WebSocket/DiscordSocketClient.Events.cs

@@ -59,12 +59,12 @@ namespace Discord.WebSocket
             remove { _messageReceivedEvent.Remove(value); }
         }
         private readonly AsyncEvent<Func<SocketMessage, Task>> _messageReceivedEvent = new AsyncEvent<Func<SocketMessage, Task>>();
-        public event Func<ulong, SocketChannel, Optional<SocketMessage>, Task> MessageDeleted
+        public event Func<ulong, ISocketMessageChannel, Optional<SocketMessage>, Task> MessageDeleted
         {
             add { _messageDeletedEvent.Add(value); }
             remove { _messageDeletedEvent.Remove(value); }
         }
-        private readonly AsyncEvent<Func<ulong, SocketChannel, Optional<SocketMessage>, Task>> _messageDeletedEvent = new AsyncEvent<Func<ulong, SocketChannel, Optional<SocketMessage>, Task>>();
+        private readonly AsyncEvent<Func<ulong, ISocketMessageChannel, Optional<SocketMessage>, Task>> _messageDeletedEvent = new AsyncEvent<Func<ulong, ISocketMessageChannel, Optional<SocketMessage>, Task>>();
         public event Func<Optional<SocketMessage>, SocketMessage, Task> MessageUpdated
         {
             add { _messageUpdatedEvent.Add(value); }

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -1293,9 +1293,9 @@ namespace Discord.WebSocket
 
                                         var msg = SocketChannelHelper.RemoveMessage(channel, this, data.Id);
                                         if (msg != null)
-                                            await _messageDeletedEvent.InvokeAsync(data.Id, channel as SocketChannel, msg).ConfigureAwait(false);
+                                            await _messageDeletedEvent.InvokeAsync(data.Id, channel, msg).ConfigureAwait(false);
                                         else
-                                            await _messageDeletedEvent.InvokeAsync(data.Id, channel as SocketChannel, Optional.Create<SocketMessage>()).ConfigureAwait(false);
+                                            await _messageDeletedEvent.InvokeAsync(data.Id, channel, Optional.Create<SocketMessage>()).ConfigureAwait(false);
                                     }
                                     else
                                     {