Bug 1598516 - Make Quitter extension retry sending the quit message in case the background script wasn't ready yet. r=mixedpuppy

Differential Revision: https://phabricator.services.mozilla.com/D55604

--HG--
extra : moz-landing-system : lando

tools/quitter/contentscript.js

@@ -7,8 +7,12 @@
 /* eslint-env webextensions */
 
 const Quitter = {
-  quit() {
-    browser.runtime.sendMessage("quit");
+  async quit() {
+    // This can be called before the background page has loaded,
+    // so we need to wait for it.
+    browser.runtime.sendMessage("quit").catch(() => {
+      setTimeout(this.quit, 100);
+    });
   },
 };