Question regarding "Part 4: File access and pickers" of the "Windows Store apps using C#/VB and XAML"

not sure what you mean by "calling the base method"?

OnNavigatedTo was generated by the template and not explicitly modified by the tutorial.

This is what it looks like:

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            navigationHelper.OnNavigatedTo(e);
        }