src/vs/platform/userDataSync/common/userDataSyncMachines.ts/UserDataSyncMachinesService/readUserData
class UserDataSyncMachinesService:	private async readUserData(manifest?: IUserDataManifest): Promise<IUserData> {
		if (this.userData) {

			const latestRef = manifest && manifest.latest ? manifest.latest[UserDataSyncMachinesService.RESOURCE] : undefined;

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

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

		return this.userDataSyncStoreService.read(UserDataSyncMachinesService.RESOURCE, this.userData);
	}