src/vs/platform/userDataSync/common/userDataSyncService.ts/UserDataSyncService/hasLocalData
class UserDataSyncService:	async hasLocalData(): Promise<boolean> {
		const result = await this.performSynchronizerAction(async synchronizer => {
			// skip global state synchronizer
			if (synchronizer.resource !== SyncResource.GlobalState && await synchronizer.hasLocalData()) {
				return true;
			}
			return undefined;
		});
		return !!result;
	}