Bug 299438 [CommonNavigator] CNF viewer state non properly reset when NCEs are activated or deactivated
The map of the objects to the NCEs should be reset whenever the NCEs associated with the viewer to change to avoid having stale label information. This has shown up when looking at the CNF tests that change the viewer.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
private ITreeContentProvider[] rootContentProviders;
	private ITreeContentProvider contentProvider;
	/*
	 * Used when providing objects to the CommonViewer by the contentProvider
	 * to record the object/description associations which are when stored
	 * in the Tree associated with the viewer.
	 */
	private Map contributionMemory;
	
	private ILabelProvider labelProvider;
	private final VisibilityAssistant assistant;
	private NavigatorFilterService navigatorFilterService;
	private INavigatorSorterService navigatorSorterService;
	private INavigatorPipelineService navigatorPipelineService;
	private INavigatorDnDService navigatorDnDService;
	private INavigatorActivationService navigatorActivationService;
	private NavigatorSaveablesService navigatorSaveablesService;
	private NavigatorExtensionStateService navigatorExtensionStateService;
	private IDescriptionProvider descriptionProvider;
	private boolean contentProviderInitialized;
	private boolean labelProviderInitialized;
	private boolean isDisposed;
	
	/**
	 * @param aViewerId
	 *            The viewer id for this content service; normally from the
	 *            <b>org.eclipse.ui.views</b> extension.
	 */
	public NavigatorContentService(String aViewerId) {
		super();