src/vs/platform/userDataSync/common/abstractSynchronizer.ts/AbstractSynchroniser/getLatestRemoteUserData
class AbstractSynchroniser:	protected async getLatestRemoteUserData(manifest: IUserDataManifest | null, lastSyncUserData: IRemoteUserData | null): Promise<IRemoteUserData> {
		if (lastSyncUserData) {

			const latestRef = manifest && manifest.latest ? manifest.latest[this.resource] : undefined;

			// Last time synced resource and latest resource on server are same
			if (lastSyncUserData.ref === latestRef) {
				return lastSyncUserData;
			}

			// There is no resource on server and last time it was synced with no resource
			if (latestRef === undefined && lastSyncUserData.syncData === null) {
				return lastSyncUserData;
			}
		}
		return this.getRemoteUserData(lastSyncUserData);
	}