Defer webview loading until all listeners have definitely been hooked…

… up on

Since webviews load on a different process, it may be possible that they load and start firing events before we have hooked up all the listeners we are interested in.

To fix, this defer setting the actual content on the webview until the listeners have been hooked up for sure

Possible cause of #98746 but since I can't repo  I can't confirm

src/vs/workbench/contrib/webview/browser/webviewElement.ts

@@ -59,13 +59,16 @@ export class IFrameWebview extends BaseWebview<HTMLIFrameElement> implements Web
 		this._register(this.on(WebviewMessageChannels.loadLocalhost, (entry: any) => {
 			this.localLocalhost(entry.origin);
 		}));
+
+		this.element!.setAttribute('src', `${this.externalEndpoint}/index.html?id=${this.id}`);
 	}
 
-	protected createElement(options: WebviewOptions, contentOptions: WebviewContentOptions) {
+	protected createElement(options: WebviewOptions, _contentOptions: WebviewContentOptions) {
+		// Do not start loading the webview yet.
+		// Wait the end of the ctor when all listeners have been hooked up.
 		const element = document.createElement('iframe');
 		element.className = `webview ${options.customClasses || ''}`;
 		element.sandbox.add('allow-scripts', 'allow-same-origin', 'allow-forms');
-		element.setAttribute('src', `${this.externalEndpoint}/index.html?id=${this.id}`);
 		element.style.border = 'none';
 		element.style.width = '100%';
 		element.style.height = '100%';

src/vs/workbench/contrib/webview/electron-browser/webviewElement.ts

@@ -267,9 +267,14 @@ export class ElectronWebviewBasedWebview extends BaseWebview<WebviewTag> impleme
 
 			this.styledFindWidget();
 		}
+
+		this.element!.preload = require.toUrl('./pre/electron-index.js');
+		this.element!.src = 'data:text/html;charset=utf-8,%3C%21DOCTYPE%20html%3E%0D%0A%3Chtml%20lang%3D%22en%22%20style%3D%22width%3A%20100%25%3B%20height%3A%20100%25%22%3E%0D%0A%3Chead%3E%0D%0A%3Ctitle%3EVirtual%20Document%3C%2Ftitle%3E%0D%0A%3C%2Fhead%3E%0D%0A%3Cbody%20style%3D%22margin%3A%200%3B%20overflow%3A%20hidden%3B%20width%3A%20100%25%3B%20height%3A%20100%25%22%20role%3D%22document%22%3E%0D%0A%3C%2Fbody%3E%0D%0A%3C%2Fhtml%3E';
 	}
 
 	protected createElement(options: WebviewOptions) {
+		// Do not start loading the webview yet.
+		// Wait the end of the ctor when all listeners have been hooked up.
 		const element = document.createElement('webview');
 
 		this._elementFocusImpl = element.focus.bind(element);