Bug 1498378 - Actually remove the old onboarding add-on's prefs r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D8598

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

browser/components/nsBrowserGlue.js

@@ -2183,7 +2183,7 @@ BrowserGlue.prototype = {
   _migrateUI: function BG__migrateUI() {
     // Use an increasing number to keep track of the current migration state.
     // Completely unrelated to the current Firefox release number.
-    const UI_VERSION = 75;
+    const UI_VERSION = 76;
     const BROWSER_DOCURL = AppConstants.BROWSER_CHROME_URL;
 
     let currentUIVersion;
@@ -2307,16 +2307,8 @@ BrowserGlue.prototype = {
       }
     }
 
-    if (currentUIVersion < 54) {
-      // Clear old onboarding prefs from profile (bug 1462415)
-      let onboardingPrefs = Services.prefs.getBranch("browser.onboarding.");
-      if (onboardingPrefs) {
-        let onboardingPrefsArray = onboardingPrefs.getChildList("");
-        for (let item of onboardingPrefsArray) {
-          Services.prefs.clearUserPref("browser.onboarding." + item);
-        }
-      }
-    }
+    // currentUIVersion < 49 and < 54 were originally used for onboarding prefs and
+    // have since then been removed and cleared in currentUIVersion < 76
 
     if (currentUIVersion < 55) {
       Services.prefs.clearUserPref("browser.customizemode.tip0.shown");
@@ -2541,6 +2533,17 @@ BrowserGlue.prototype = {
       Services.prefs.setIntPref("browser.livebookmarks.migrationAttemptsLeft", 5);
     }
 
+    if (currentUIVersion < 76) {
+      // Clear old onboarding prefs from profile (bug 1462415)
+      let onboardingPrefs = Services.prefs.getBranch("browser.onboarding.");
+      if (onboardingPrefs) {
+        let onboardingPrefsArray = onboardingPrefs.getChildList("");
+        for (let item of onboardingPrefsArray) {
+          Services.prefs.clearUserPref("browser.onboarding." + item);
+        }
+      }
+    }
+
     // Update the migration version.
     Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
   },