arc: Show migration success notification on the next sign-in after migration.

chrome/browser/chromeos/arc/arc_migration_guide_notification.h

Index: chrome/browser/chromeos/arc/arc_migration_guide_notification.h
diff --git a/chrome/browser/chromeos/arc/arc_migration_guide_notification.h b/chrome/browser/chromeos/arc/arc_migration_guide_notification.h
index cf26fca581d38ddb714b6948c3db226749dfdcb5..61760d9a9b1c6b3b9435cb8a5f60d5bfce2bf8a7 100644
--- a/chrome/browser/chromeos/arc/arc_migration_guide_notification.h
+++ b/chrome/browser/chromeos/arc/arc_migration_guide_notification.h
@@ -14,6 +14,12 @@ namespace arc {
 // due to the file system incompatibility.
 void ShowArcMigrationGuideNotification(Profile* profile);
 
+// Shows a one-time notification when this is the first sign-in after the
+// migration has happend successfully. It records the fact to the pref that no
+// more notification is necessary, either when it showed the notification or
+// when the profile is newly created on the compatible filesystem.
+void ShowArcMigrationSuccessNotificationIfNeeded(Profile* profile);
+
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_ARC_MIGRATION_GUIDE_NOTIFICATION_H_