src/vs/platform/userDataSync/common/userDataSyncService.ts/ManualSyncTask/getPreviews
class ManualSyncTask:	private async getPreviews(token: CancellationToken): Promise<[SyncResource, ISyncResourcePreview][]> {
		const result: [SyncResource, ISyncResourcePreview][] = [];
		const remoteUserDataSyncConfiguration: IUserDataSyncConfiguration = await this.getUserDataSyncConfiguration();
		for (const synchroniser of this.synchronisers) {
			if (token.isCancellationRequested) {
				return [];
			}
			const preview = await synchroniser.preview(this.manifest, remoteUserDataSyncConfiguration, this.syncHeaders);
			if (preview) {
				result.push(this.toSyncResourcePreview(synchroniser.resource, preview));
			}
		}
		return result;
	}