src/vs/workbench/api/browser/viewsExtensionPoint.ts/ViewsExtensionHandler/deregisterCustomViewContainer
class ViewsExtensionHandler:	private deregisterCustomViewContainer(viewContainer: ViewContainer): void {
		this.viewContainersRegistry.deregisterViewContainer(viewContainer);
		Registry.as<ViewletRegistry>(ViewletExtensions.Viewlets).deregisterViewlet(viewContainer.id);
	}