Bug 271799 Replace IBackgroundRunner/IRunnableWithProgress with equinox.concurrent APIs
These basic abstractions of "something I want to run", and "someone who can run things" tend to get reinvented in various components. We should consolidate on the simple low level Equinox APIs for consistency.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/workbench/ui/internal/Activator.java
private ServiceTracker locationTracker;
	private ServiceTracker debugTracker;
	private static Activator activator;
	/**
	 * Get the default activator.
	 * 
	 * @return a BundleActivator
	 */
	public static Activator getDefault() {
		return activator;
	}
	/**
	 * @return this bundles context
	 */
	public BundleContext getContext() {
		return context;
	}
	/**
	 * @return the bundle object
	 */
	public Bundle getBundle() {
		return context.getBundle();
	}
	public void start(BundleContext context) throws Exception {
		activator = this;
		this.context = context;
	}
	public void stop(BundleContext context) throws Exception {
		if (pkgAdminTracker != null) {
			pkgAdminTracker.close();