[UPMLocalPwd] Clean up the unused migration warning prefs (pt 11)

The prefs stopped being used in crrev.com/c/6239110 so they are
deprecated.

Note: I've followed the guidelines from the README
https://chromium.googlesource.com/chromium/src/+/HEAD/chrome/browser/prefs/README.md#deleting-an-old-pref
The last step would be to clean up prefs older than a year, but there
were no prefs from February 2024 or older left to clean up so I don't
have a follow up step for that.

Bug: 377285449
Change-Id: Ie67b10c2ec7f2d1b6d6335523c8bc64d6067f0f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6243759
Reviewed-by: Ioana Pandele <[email protected]>
Reviewed-by: Dominic Battré <[email protected]>
Commit-Queue: Ivana Žužić <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1418078}
diff --git a/chrome/browser/password_manager/android/local_passwords_migration_warning_util.cc b/chrome/browser/password_manager/android/local_passwords_migration_warning_util.cc
index 0668a9e..32610f5 100644
--- a/chrome/browser/password_manager/android/local_passwords_migration_warning_util.cc
+++ b/chrome/browser/password_manager/android/local_passwords_migration_warning_util.cc
@@ -59,7 +59,7 @@
 
   // The post password migration sheet should be shown for an active UPM user
   // that uses split stores only once, so
-  // `kLocalPasswordMigrationWarningShownAtStartup` will be true only when the
+  // `kShouldShowPostPasswordMigrationSheetAtStartup` will be true only when the
   // migration algorithm sets it to true and it will be flipped to false when
   // the sheet is shown.
   return profile->GetPrefs()->GetBoolean(
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index ea871f7..745c2ce 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1092,6 +1092,14 @@
 inline constexpr char kUserAgentClientHintsGREASEUpdateEnabled[] =
     "policy.user_agent_client_hints_grease_update_enabled";
 
+#if BUILDFLAG(IS_ANDROID)
+// Deprecated 2/2025.
+inline constexpr char kLocalPasswordsMigrationWarningShownTimestamp[] =
+    "local_passwords_migration_warning_shown_timestamp";
+inline constexpr char kLocalPasswordMigrationWarningShownAtStartup[] =
+    "local_passwords_migration_warning_shown_at_startup";
+#endif  // BUILDFLAG(IS_ANDROID)
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1519,6 +1527,14 @@
   // Deprecated 01/2025.
   registry->RegisterBooleanPref(kUsedPolicyCertificates, false);
 #endif  // BUILDFLAG(IS_CHROMEOS)
+
+#if BUILDFLAG(IS_ANDROID)
+  // Deprecated 02/2025.
+  registry->RegisterTimePref(kLocalPasswordsMigrationWarningShownTimestamp,
+                             base::Time());
+  registry->RegisterBooleanPref(kLocalPasswordMigrationWarningShownAtStartup,
+                                false);
+#endif  // BUILDFLAG(IS_ANDROID)
 }
 
 }  // namespace
@@ -2798,6 +2814,12 @@
   profile_prefs->ClearPref(kUsedPolicyCertificates);
 #endif  // BUILDFLAG(IS_CHROMEOS)
 
+#if BUILDFLAG(IS_ANDROID)
+  // Added 02/2025.
+  profile_prefs->ClearPref(kLocalPasswordsMigrationWarningShownTimestamp);
+  profile_prefs->ClearPref(kLocalPasswordMigrationWarningShownAtStartup, );
+#endif  // BUILDFLAG(IS_ANDROID)
+
   // Please don't delete the following line. It is used by PRESUBMIT.py.
   // END_MIGRATE_OBSOLETE_PROFILE_PREFS
 
diff --git a/components/password_manager/core/browser/password_manager.cc b/components/password_manager/core/browser/password_manager.cc
index 739a8f5..f25a42c 100644
--- a/components/password_manager/core/browser/password_manager.cc
+++ b/components/password_manager/core/browser/password_manager.cc
@@ -424,10 +424,6 @@
   registry->RegisterStringPref(prefs::kUPMErrorUIShownTimestamp, "0");
   registry->RegisterBooleanPref(
       prefs::kUserAcknowledgedLocalPasswordsMigrationWarning, false);
-  registry->RegisterTimePref(
-      prefs::kLocalPasswordsMigrationWarningShownTimestamp, base::Time());
-  registry->RegisterBooleanPref(
-      prefs::kLocalPasswordMigrationWarningShownAtStartup, false);
   registry->RegisterIntegerPref(
       prefs::kLocalPasswordMigrationWarningPrefsVersion, 0);
   registry->RegisterIntegerPref(
diff --git a/components/password_manager/core/common/password_manager_pref_names.h b/components/password_manager/core/common/password_manager_pref_names.h
index d201539..7904905 100644
--- a/components/password_manager/core/common/password_manager_pref_names.h
+++ b/components/password_manager/core/common/password_manager_pref_names.h
@@ -189,17 +189,6 @@
     "local.password_hash_data_list";
 
 #if BUILDFLAG(IS_ANDROID)
-// The timestamp at which the last UPM local passwords migration warning was
-// shown to the user in microseconds since Windows epoch. This is needed to
-// ensure that the UI is prompted only once per given time interval (currently
-// one month).
-inline constexpr char kLocalPasswordsMigrationWarningShownTimestamp[] =
-    "local_passwords_migration_warning_shown_timestamp";
-
-// Whether the local password migration warning was already shown at startup.
-inline constexpr char kLocalPasswordMigrationWarningShownAtStartup[] =
-    "local_passwords_migration_warning_shown_at_startup";
-
 // The version of the password migration warning prefs.
 inline constexpr char kLocalPasswordMigrationWarningPrefsVersion[] =
     "local_passwords_migration_warning_reset_count";