src/vs/platform/environment/common/environmentService.ts/AbstractNativeEnvironmentService/extensionsDownloadLocation
class AbstractNativeEnvironmentService:	get extensionsDownloadLocation(): URI {
		const cliExtensionsDownloadDir = this.args['extensions-download-dir'];
		if (cliExtensionsDownloadDir) {
			return URI.file(resolve(cliExtensionsDownloadDir));
		}

		return URI.file(join(this.userDataPath, 'CachedExtensionVSIXs'));
	}