function connectTo(sendPort) {
    var channel = null;
    if (sendPort) {
      channel = new wtf.ipc.MessageChannel(window, sendPort);
      channel.postMessage({
        'hello': true
      });
    }
    callback.call(opt_scope, channel);
  }
Connects to the window that opened this window, if any.
When running inside a Chrome extension this will connect to the background
page.
@param {!function(this: T, wtf.ipc.Channel)} callback Connect callback.
@param {T=} opt_scope Scope for the callback.
@template T