src/vs/platform/userDataSync/common/globalStateSync.ts/GlobalStateSynchroniser/getStorageKeys
class GlobalStateSynchroniser:	private async getStorageKeys(lastSyncGlobalState: IGlobalState | null): Promise<StorageKeys> {
		const storageData = await this.userDataProfileStorageService.readStorageData(this.syncResource.profile);
		const user: string[] = [], machine: string[] = [];
		for (const [key, value] of storageData) {
			if (value.target === StorageTarget.USER) {
				user.push(key);
			} else if (value.target === StorageTarget.MACHINE) {
				machine.push(key);
			}
		}
		const registered = [...user, ...machine];
		const unregistered = lastSyncGlobalState?.storage ? Object.keys(lastSyncGlobalState.storage).filter(key => !key.startsWith(argvStoragePrefx) && !registered.includes(key) && storageData.get(key) !== undefined) : [];

		if (!isWeb) {
			// Following keys are synced only in web. Do not sync these keys in other platforms
			const keysSyncedOnlyInWeb = [...ALL_SYNC_RESOURCES.map(resource => getEnablementKey(resource)), SYNC_SERVICE_URL_TYPE];
			unregistered.push(...keysSyncedOnlyInWeb);
			machine.push(...keysSyncedOnlyInWeb);
		}

		return { user, machine, unregistered };
	}