src/vs/workbench/services/history/browser/history.ts/HistoryService/matchesEditor
class HistoryService:	private matchesEditor(identifier: IEditorIdentifier, editor?: IEditorPane): boolean {
		if (!editor || !editor.group) {
			return false;
		}

		if (identifier.groupId !== editor.group.id) {
			return false;
		}

		return editor.input ? identifier.editor.matches(editor.input) : false;
	}