public VisualStudioDocumentTrackingService(IServiceProvider serviceProvider)
        {
            _tracker = new NonRoslynTextBufferTracker(this);

            _visibleFrames = ImmutableList <FrameListener> .Empty;

            _monitorSelection = (IVsMonitorSelection)serviceProvider.GetService(typeof(SVsShellMonitorSelection));
            _monitorSelection.AdviseSelectionEvents(this, out _cookie);
        }
        public VisualStudioDocumentTrackingService(IServiceProvider serviceProvider)
        {
            _tracker = new NonRoslynTextBufferTracker(this);

            _visibleFrames = ImmutableList<FrameListener>.Empty;

            _monitorSelection = (IVsMonitorSelection)serviceProvider.GetService(typeof(SVsShellMonitorSelection));
            _monitorSelection.AdviseSelectionEvents(this, out _cookie);
        }