Bug 1917495 - Port bug 1642039: Make lastUpdateInstalled asynchronous. r=darktrojan

Differential Revision: https://phabricator.services.mozilla.com/D221414

--HG--
extra : amend_source : 34a269c9f2708d58781d2e1430345d835d548fc7

mail/base/content/specialTabs.js

@@ -1018,7 +1018,7 @@ var specialTabs = {
    *
    * @see {BrowserContentHandler.needHomepageOverride}
    */
-  showWhatsNewPage() {
+  async showWhatsNewPage() {
     const old_mstone = Services.prefs.getCharPref(
       "mailnews.start_page_override.mstone",
       ""
@@ -1033,7 +1033,7 @@ var specialTabs = {
       const um = Cc["@mozilla.org/updates/update-manager;1"].getService(
         Ci.nsIUpdateManager
       );
-      const update = um.lastUpdateInstalled;
+      const update = await um.lastUpdateInstalled();
 
       if (
         update &&

mail/test/browser/update/browser_showWhatsNewPageTest.js

@@ -155,7 +155,7 @@ async function WnpTest({
   logTestInfo(`Set appinfo to use version=${Services.appinfo.version}`);
 
   reloadUpdateManagerData(false);
-  window.specialTabs.showWhatsNewPage();
+  await window.specialTabs.showWhatsNewPage();
 
   if (expectedPostUpdatePage !== NO_POST_UPDATE_PAGE) {
     const postUpdatePage = await uriResolver.promise;