src/vs/workbench/contrib/webview/browser/webview.ts/WebviewOriginStore/getOrigin
class WebviewOriginStore:	public getOrigin(viewType: string, additionalKey: string | undefined): string {
		const key = this._getKey(viewType, additionalKey);

		const existing = this._state[key];
		if (existing && typeof existing === 'string') {
			return existing;
		}

		const newOrigin = generateUuid();
		this._state[key] = newOrigin;
		this._memento.saveMemento();
		return newOrigin;
	}