src/vs/workbench/contrib/mergeEditor/browser/commands/commands.ts/ShowHideTopBase/constructor
class ShowHideTopBase:	constructor() {
		super({
			id: 'merge.showBaseTop',
			title: {
				value: localize('layout.showBaseTop', 'Show Base Top'),
				original: 'Show Base Top',
			},
			toggled: ContextKeyExpr.and(ctxMergeEditorShowBase, ctxMergeEditorShowBaseAtTop),
			menu: [
				{
					id: MenuId.EditorTitle,
					when: ContextKeyExpr.and(ctxIsMergeEditor, ctxMergeEditorLayout.isEqualTo('mixed')),
					group: '2_merge',
					order: 10,
				},
			],
		});
	}