src/vs/workbench/contrib/notebook/browser/view/renderers/backLayerWebView.ts/BackLayerWebView/initializeMarkup
class BackLayerWebView:	async initializeMarkup(cells: readonly IMarkupCellInitialization[]): Promise<void> {
		if (this._disposed) {
			return;
		}

		this.initializeMarkupPromise?.p.complete();
		const requestId = UUID.generateUuid();
		this.initializeMarkupPromise = { p: new DeferredPromise(), requestId, isFirstInit: this.firstInit };

		if (this._webviewPreloadInitialized) {
			// wait for webview preload script module to be loaded
			await this._webviewPreloadInitialized.p;
		}

		this.firstInit = false;

		for (const cell of cells) {
			this.markupPreviewMapping.set(cell.cellId, cell);
		}

		this._sendMessageToWebview({
			type: 'initializeMarkup',
			cells,
			requestId,
		});

		return this.initializeMarkupPromise.p.p;
	}