Method AddObserver

src/butil/observer_list.h:119–126

Add an observer to the list. An observer should not be added to the same list more than once.

  // Add an observer to the list.  An observer should not be added to
  // the same list more than once.
  void AddObserver(ObserverType* obs) {
    if (std::find(observers_.begin(), observers_.end(), obs)
        != observers_.end()) {
      NOTREACHED() << "Observers can only be added once!";
      return;
    }
    observers_.push_back(obs);
  }

  // Remove an observer from the list if it is in the list.
  void RemoveObserver(ObserverType* obs) {