diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index e90df1f..1a50a5ef 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -18,7 +18,6 @@
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/accessibility/accessibility_labels_service.h"
 #include "chrome/browser/accessibility/invert_bubble_prefs.h"
-#include "chrome/browser/ash/notifications/update_notification_showing_controller.h"
 #include "chrome/browser/browser_process_impl.h"
 #include "chrome/browser/chrome_content_browser_client.h"
 #include "chrome/browser/chromeos/enterprise/cloud_storage/policy_utils.h"
@@ -986,6 +985,12 @@
     "cached_fonts.search_results_page.fallback";
 #endif  // BUILDFLAG(IS_WIN)
 
+// Deprecated 01/2024.
+#if BUILDFLAG(IS_CHROMEOS_ASH)
+constexpr char kUpdateNotificationLastShownMilestone[] =
+    "update_notification_last_shown_milestone";
+#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1399,6 +1404,11 @@
   registry->RegisterListPref(kSearchResultsPagePrimaryFontsPref);
   registry->RegisterListPref(kSearchResultsPageFallbackFontsPref);
 #endif
+
+  // Deprecated 01/2024.
+#if BUILDFLAG(IS_CHROMEOS_ASH)
+  registry->RegisterIntegerPref(kUpdateNotificationLastShownMilestone, -10);
+#endif
 }
 
 void ClearSyncRequestedPrefAndMaybeMigrate(PrefService* profile_prefs) {
@@ -1974,7 +1984,6 @@
   ash::ServicesCustomizationDocument::RegisterProfilePrefs(registry);
   ash::settings::OSSettingsUI::RegisterProfilePrefs(registry);
   ash::StartupUtils::RegisterOobeProfilePrefs(registry);
-  ash::UpdateNotificationShowingController::RegisterProfilePrefs(registry);
   ash::user_image::prefs::RegisterProfilePrefs(registry);
   ash::UserImageSyncObserver::RegisterProfilePrefs(registry);
   ChromeMetricsServiceClient::RegisterProfilePrefs(registry);
@@ -2654,6 +2663,11 @@
   profile_prefs->ClearPref(kSearchResultsPageFallbackFontsPref);
 #endif
 
+  // Deprecated 01/2024.
+#if BUILDFLAG(IS_CHROMEOS_ASH)
+  profile_prefs->ClearPref(kUpdateNotificationLastShownMilestone);
+#endif
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_PROFILE_PREFS