Bug 1996449 - Ensure runOncePerModification("displayMenuBar", ..) works as expected. r=mkaply,mossop

runOncePerModification works on strings. If you pass a boolean down it
will always call its callback (because "true" != true etc).

Differential Revision: https://phabricator.services.mozilla.com/D271452

Author: emilio

browser/components/enterprisepolicies/Policies.sys.mjs

@@ -3177,6 +3177,8 @@ export function runOnce(actionName, callback) {
  *        A promise that will resolve once the callback finishes running.
  */
 async function runOncePerModification(actionName, policyValue, callback) {
+  // Stringify the value so that it matches what we'd get from getStringPref.
+  policyValue = policyValue + "";
   let prefName = `browser.policies.runOncePerModification.${actionName}`;
   let oldPolicyValue = Services.prefs.getStringPref(prefName, undefined);
   if (policyValue === oldPolicyValue) {

browser/components/enterprisepolicies/tests/browser/browser_policy_display_menu.js

@@ -28,11 +28,22 @@ add_task(async function test_menu_shown_string() {
 
   // Since testing will apply the policy after the browser has already started,
   // we will need to open a new window to actually see the menu bar
-  let newWin = await BrowserTestUtils.openNewBrowserWindow();
-  let menubar = newWin.document.getElementById("toolbar-menubar");
-  ok(!menubar.hasAttribute("autohide"), "The menu bar should not be hidden");
+  {
+    let newWin = await BrowserTestUtils.openNewBrowserWindow();
+    let menubar = newWin.document.getElementById("toolbar-menubar");
+    ok(!menubar.hasAttribute("autohide"), "The menu bar should not be hidden");
+    setToolbarVisibility(menubar, false);
+    ok(menubar.hasAttribute("autohide"), "The menu bar should be hidden");
+    await BrowserTestUtils.closeWindow(newWin);
+  }
 
-  await BrowserTestUtils.closeWindow(newWin);
+  {
+    // Make sure the menubar autohide persists even tho it's default-on.
+    let newWin = await BrowserTestUtils.openNewBrowserWindow();
+    let menubar = newWin.document.getElementById("toolbar-menubar");
+    ok(menubar.hasAttribute("autohide"), "The menu bar should be hidden");
+    await BrowserTestUtils.closeWindow(newWin);
+  }
 });
 
 add_task(async function test_menubar_on() {