[Bedtime Hours] Deprecate unused pref

... kDeviceRestrictionScheduleHighestSeenTime

Followed chrome/browser/prefs/README.md#deleting-an-old-pref

Bug: b:405344789
Change-Id: Iadaf0770a80fd79b92d262fc9116ddc7d7973e88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6381735
Reviewed-by: Dominic Battré <[email protected]>
Reviewed-by: Denis Kuznetsov <[email protected]>
Commit-Queue: Ivan Šandrk <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1436088}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 2b45788..a8cd211 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1101,6 +1101,12 @@
 inline constexpr char kAutoEnrollmentPowerLimit[] = "AutoEnrollmentPowerLimit";
 #endif  // BUILDFLAG(IS_CHROMEOS)
 
+#if BUILDFLAG(IS_CHROMEOS)
+// Deprecated 03/2025.
+inline constexpr char kDeviceRestrictionScheduleHighestSeenTime[] =
+    "device_restriction_schedule_highest_seen_time";
+#endif  // BUILDFLAG(IS_CHROMEOS)
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1205,6 +1211,12 @@
   registry->RegisterBooleanPref(kShouldAutoEnroll, false);
   registry->RegisterIntegerPref(kAutoEnrollmentPowerLimit, -1);
 #endif
+
+#if BUILDFLAG(IS_CHROMEOS)
+  // Deprecated 03/2025.
+  registry->RegisterTimePref(kDeviceRestrictionScheduleHighestSeenTime,
+                             base::Time());
+#endif
 }
 
 // Register prefs used only for migration (clearing or moving to a new key).
@@ -2450,6 +2462,11 @@
   local_state->ClearPref(kAutoEnrollmentPowerLimit);
 #endif
 
+  // Added 03/2025.
+#if BUILDFLAG(IS_CHROMEOS)
+  local_state->ClearPref(kDeviceRestrictionScheduleHighestSeenTime);
+#endif
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_LOCAL_STATE_PREFS