src/vs/workbench/services/userData/browser/userDataInit.ts/ExtensionsPreviewInitializer/getPreview
class ExtensionsPreviewInitializer:	getPreview(): Promise<IExtensionsInitializerPreviewResult | null> {
		if (!this.previewPromise) {
			this.previewPromise = super.initialize(this.extensionsData).then(() => this.preview);
		}
		return this.previewPromise;
	}