src/vs/workbench/browser/layout.ts/Layout/hasViews
class Layout:	private hasViews(id: string): boolean {
		const viewContainer = this.viewDescriptorService.getViewContainerById(id);
		if (!viewContainer) {
			return false;
		}

		const viewContainerModel = this.viewDescriptorService.getViewContainerModel(viewContainer);
		if (!viewContainerModel) {
			return false;
		}

		return viewContainerModel.activeViewDescriptors.length >= 1;
	}