Merge pull request microsoft#154474 from microsoft/joh/issue137884

Author: jrieken

src/vs/workbench/services/extensions/browser/webWorkerExtensionHost.ts

@@ -82,7 +82,15 @@ export class WebWorkerExtensionHost extends Disposable implements IExtensionHost
 	}
 
 	private async _getWebWorkerExtensionHostIframeSrc(): Promise<string> {
-		const suffix = this._environmentService.debugExtensionHost && this._environmentService.debugRenderer ? '?debugged=1' : '?';
+		const suffixSearchParams = new URLSearchParams();
+		if (this._environmentService.debugExtensionHost && this._environmentService.debugRenderer) {
+			suffixSearchParams.set('debugged', '1');
+		}
+		if (globalThis.crossOriginIsolated) {
+			suffixSearchParams.set('vscode-coi', '3' /*COOP+COEP*/);
+		}
+		const suffix = `?${suffixSearchParams.toString()}`;
+
 		const iframeModulePath = 'vs/workbench/services/extensions/worker/webWorkerExtensionHostIframe.html';
 		if (platform.isWeb) {
 			const webEndpointUrlTemplate = this._productService.webEndpointUrlTemplate;

src/vs/workbench/services/extensions/worker/webWorkerExtensionHostIframe.html

@@ -66,7 +66,11 @@
 
 	function start() {
 		try {
-			const worker = new Worker('../../../../base/worker/workerMain.js', { name });
+			const workerUrl = new URL('../../../../base/worker/workerMain.js');
+			if(crossOriginIsolated) {
+				workerUrl.searchParams.set('vscode-coi', 2 /*COEP*/)
+			}
+			const worker = new Worker(workerUrl.toString(), { name });
 			worker.postMessage('vs/workbench/api/worker/extensionHostWorker');
 			const nestedWorkers = new Map();