Bug 205049 Other plug-ins should be able to define default content generator
Currently only the content generator can define which plug-ins it can be the default for - we need a way for plug-ins to refer back to the marker support for thier own generator.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/MarkerContentGenerator.java
Collection filters = getEnabledFilters();
		Collection returnMarkers = null;
		if (filters.size() > 0) {
			Iterator filtersIterator = filters.iterator();
			if (andFilters) {
				Collection matching = new HashSet();
				while (filtersIterator.hasNext()) {
					computeMarkers(matching, subMonitor,
							(MarkerFieldFilterGroup) filtersIterator.next());
					if (returnMarkers == null)
						returnMarkers = new HashSet(matching);
					else
						findIntersection(matching, returnMarkers);
					matching.clear();
				}
			} else {
				returnMarkers = new HashSet();
				while (filtersIterator.hasNext()) {
					computeMarkers(returnMarkers, subMonitor,
							(MarkerFieldFilterGroup) filtersIterator.next());
				}
			}
		} else
			returnMarkers = computeAllMarkers(subMonitor);
		MarkerEntry[] entries = new MarkerEntry[returnMarkers.size()];
		Iterator markers = returnMarkers.iterator();
		int index = 0;
		
		while (markers.hasNext()) {
			entries[index] = new MarkerEntry((IMarker) markers.next());