notifyNewMessageComing method

dynamic notifyNewMessageComing(
  1. String firstKey,
  2. int newMsgCount

New message first key When reach new message, the count will be disppear For example if new message {id: 1},{id:2},{id:3}, the key should be 1 if hasPrevMsgs is true, widget can calc the count, we need simple increase newMsgCount


notifyNewMessageComing(String firstKey, int newMsgCount) {
  _handleNewMessageComing(firstKey, newMsgCount);