There's a trampoline method like this, where |sender_| is a weak pointer:

void SpeechRecognitionDispatcherHost::Send(IPC::Message* message) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);
  // The weak ptr must only be accessed on the UI thread.
  BrowserThread::PostTask(
      BrowserThread::UI, FROM_HERE,
      base::BindOnce(base::IgnoreResult(&IPC::Sender::Send), sender_, message));

|message| is an owning raw pointer (a convention of Chrome legacy IPC). If the task is cancelled after being posted, the message is leaked.