src/vs/platform/backup/electron-main/backupMainService.ts/BackupMainService/registerFolderBackupSync
class BackupMainService:	registerFolderBackupSync(folderInfo: IFolderBackupInfo): string {
		if (!this.folders.some(folder => this.backupUriComparer.isEqual(folderInfo.folderUri, folder.folderUri))) {
			this.folders.push(folderInfo);
			this.saveSync();
		}

		return this.getBackupPath(this.getFolderHash(folderInfo));
	}