src/vs/platform/userDataSync/common/abstractSynchronizer.ts/AbstractSynchroniser/backupLocal
class AbstractSynchroniser:	protected async backupLocal(content: string): Promise<void> {
		const syncData: ISyncData = { version: this.version, content };
		return this.userDataSyncBackupStoreService.backup(this.resource, JSON.stringify(syncData));
	}