allow CORS from PRSS CDN (microsoft#200627)

fixes microsoft/vscode-remote-release#9246

Author: joaomoreno

src/vs/code/electron-main/app.ts

@@ -301,6 +301,24 @@ export class CodeApplication extends Disposable {
 
 		//#endregion
 
+		//#region Allow CORS for the PRSS CDN
+
+		// https://github.com/microsoft/vscode-remote-release/issues/9246
+		session.defaultSession.webRequest.onHeadersReceived((details, callback) => {
+			if (details.url.startsWith('https://vscode.download.prss.microsoft.com/')) {
+				const responseHeaders = details.responseHeaders ?? Object.create(null);
+
+				if (responseHeaders['Access-Control-Allow-Origin'] === undefined) {
+					responseHeaders['Access-Control-Allow-Origin'] = ['*'];
+					return callback({ cancel: false, responseHeaders });
+				}
+			}
+
+			return callback({ cancel: false });
+		});
+
+		//#endregion
+
 		//#region Code Cache
 
 		type SessionWithCodeCachePathSupport = Session & {