src/vs/workbench/services/userData/browser/userDataInit.ts/UserDataInitializationService/initializeInstalledExtensions
class UserDataInitializationService:	async initializeInstalledExtensions(instantiationService: IInstantiationService): Promise<void> {
		if (!this.initializeInstalledExtensionsPromise) {
			this.initializeInstalledExtensionsPromise = (async () => {
				this.logService.trace(`UserDataInitializationService#initializeInstalledExtensions`);
				const extensionsPreviewInitializer = await this.getExtensionsPreviewInitializer(instantiationService);
				if (extensionsPreviewInitializer) {
					await instantiationService.createInstance(InstalledExtensionsInitializer, extensionsPreviewInitializer).initialize();
				}
			})();
		}
		return this.initializeInstalledExtensionsPromise;
	}