Bug 1700106 - [devtools] Remove the balanced-observers eslint disabling from DevTools mochitests. r=jdescottes

Differential Revision: https://phabricator.services.mozilla.com/D109476

devtools/.eslintrc.mochitests.js

@@ -11,8 +11,6 @@ module.exports = {
   rules: {
     // Allow non-camelcase so that run_test doesn't produce a warning.
     camelcase: "off",
-    // Tests don't have to cleanup observers
-    "mozilla/balanced-observers": 0,
     // Tests can always import anything.
     "mozilla/reject-some-requires": 0,
   },

devtools/server/tests/browser/browser_navigateEvents.js

@@ -112,6 +112,9 @@ var httpObserver = function(subject, topic, state) {
   }
 };
 Services.obs.addObserver(httpObserver, "http-on-modify-request");
+registerCleanupFunction(() => {
+  Services.obs.removeObserver(httpObserver, "http-on-modify-request");
+});
 
 function onMessage({ data }) {
   assertEvent(data.event, data.data);

devtools/startup/tests/browser/browser_shim_disable_devtools.js

@@ -113,7 +113,10 @@ function waitForDelayedStartupFinished(win) {
   return new Promise(resolve => {
     Services.obs.addObserver(function observer(subject, topic) {
       if (win == subject) {
-        Services.obs.removeObserver(observer, topic);
+        Services.obs.removeObserver(
+          observer,
+          "browser-delayed-startup-finished"
+        );
         resolve();
       }
     }, "browser-delayed-startup-finished");