Backed out 2 changesets (bug 1809464, bug 1644104) for causing failures at test_principal.html.

Backed out changeset f537b6744b81 (bug 1644104)
Backed out changeset c56d2c4b4f77 (bug 1809464)

modules/libpref/init/StaticPrefList.yaml

@@ -252,7 +252,7 @@
 # notifications are used.
 - name: alerts.useSystemBackend
   type: bool
-#if defined(XP_WIN) && !defined(NIGHTLY_BUILD)
+#ifdef XP_WIN
   # Linux and macOS turn on system level notification as default, but Windows is
   # disabled due to instability (dependencies of bug 1497425).
   value: false
@@ -261,14 +261,6 @@
 #endif
   mirror: always
 
-#if defined(XP_WIN) && defined(NIGHTLY_BUILD)
- # On Windows, a COM Surrogate notification server receives notification events
- # and can relaunch the application after it has been closed.
-- name: alerts.useSystemBackend.windows.notificationserver.enabled
-  type: bool
-  value: true
-  mirror: never
-#endif
 
 #ifdef ANDROID
   #---------------------------------------------------------------------------

toolkit/components/alerts/test/test_principal.html

@@ -88,17 +88,18 @@ async function testNodePrincipal() {
   is(source, localizedSource, "Should include source for node principal");
 }
 
-  async function runTest() {
+function runTest() {
   if (!("@mozilla.org/alerts-service;1" in Cc)) {
     todo(false, "Alerts service does not exist in this application");
     return;
   }
 
-  ok(true, "Alerts service exists in this application");
+  if ("@mozilla.org/system-alerts-service;1" in Cc) {
+    todo(false, "Native alerts service exists in this application");
+    return;
+  }
 
-  await SpecialPowers.pushPrefEnv({
-    set: [["alerts.useSystemBackend", false]],
-  });
+  ok(true, "Alerts service exists in this application");
 
   // sendSyncMessage returns an array of arrays. See the comments in
   // test_alerts_noobserve.html and test_SpecialPowersLoadChromeScript.html.

widget/windows/tests/unit/test_windows_alert_service.js

@@ -247,10 +247,10 @@ function testAlert(when, { serverEnabled, profD, isBackgroundTaskMode } = {}) {
 }
 
 add_task(async () => {
-  Services.prefs.deleteBranch(
+  Services.prefs.clearUserPref(
     "alerts.useSystemBackend.windows.notificationserver.enabled"
   );
-  testAlert("when notification server pref is unset", {
+  testAlert("when notification server pref is unset (i.e., default)", {
     profD: gProfD,
   });