Apply the namespace migration for "savefile.default_directory" user-pref as well.

chrome/browser/chromeos/preferences_unittest.cc

Index: chrome/browser/chromeos/preferences_unittest.cc
diff --git a/chrome/browser/chromeos/preferences_unittest.cc b/chrome/browser/chromeos/preferences_unittest.cc
index 53d036c23532060014a3073054f21a811e83e1fa..9bc6077a23a3f9a7a88174613d8c9897ffd6fa56 100644
--- a/chrome/browser/chromeos/preferences_unittest.cc
+++ b/chrome/browser/chromeos/preferences_unittest.cc
@@ -6,6 +6,7 @@
 
 #include "base/prefs/pref_member.h"
 #include "chrome/browser/chromeos/input_method/mock_input_method_manager.h"
+#include "chrome/browser/download/chrome_download_manager_delegate.h"
 #include "chrome/browser/download/download_prefs.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_pref_service_syncable.h"
@@ -58,6 +59,7 @@ TEST(PreferencesTest, TestUpdatePrefOnBrowserScreenDetails) {
   TestingPrefServiceSyncable prefs;
   Preferences::RegisterUserPrefs(prefs.registry());
   DownloadPrefs::RegisterUserPrefs(prefs.registry());
+  ChromeDownloadManagerDelegate::RegisterUserPrefs(prefs.registry());
   // kSelectFileLastDirectory is registered for Profile. Here we register it for
   // testing.
   prefs.registry()->RegisterStringPref(prefs::kSelectFileLastDirectory,