p13n: rm seapen wallpaper file migration

Before public launch, SeaPen image files were stored outside of user
cryptohome. These files were mv'd to a secure directory in cryptohome
so that early testers would not lose their generated images when the
directories were changed. This migration code is no longer necessary
since ChromeOS 125.

OBSOLETE_HISTOGRAM[Ash.SeaPen.MigrationStatus]=no longer needed
BUG=b:373640304

Change-Id: I3f0eaccd416b42cb05a89dea70b6556985b1a45d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5932395
Reviewed-by: Jason Thai <[email protected]>
Reviewed-by: Xiaoqian Dai <[email protected]>
Commit-Queue: Jeffrey Young <[email protected]>
Reviewed-by: Dominic Battré <[email protected]>
Reviewed-by: Yulun Wu <[email protected]>
Reviewed-by: Thuong Phan <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1372826}
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index cf8da9a..4ad259b 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -1151,6 +1151,12 @@
 // Deprecated 10/2024.
 inline constexpr char kDocumentSuggestEnabled[] = "documentsuggest.enabled";
 
+#if BUILDFLAG(IS_CHROMEOS_ASH)
+// Deprecated 10/2024
+inline constexpr char kWallpaperSeaPenMigrationStatus[] =
+    "ash.wallpaper.sea_pen.migration_status";
+#endif
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -1630,6 +1636,9 @@
 #if BUILDFLAG(IS_CHROMEOS_ASH)
   // Deprecated 10/2024
   registry->RegisterIntegerPref(kAccessibilityFaceGazeCursorSmoothing, 7);
+
+  // Deprecated 10/2024
+  registry->RegisterIntegerPref(kWallpaperSeaPenMigrationStatus, 0);
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)
 
   // Deprecated 10/2024
@@ -3005,6 +3014,9 @@
 #if BUILDFLAG(IS_CHROMEOS_ASH)
   // Added 10/2024
   profile_prefs->ClearPref(kAccessibilityFaceGazeCursorSmoothing);
+
+  // Added 10/2024
+  profile_prefs->ClearPref(kWallpaperSeaPenMigrationStatus);
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)
 
   // Added 10/2024