Remove the last usages of PrefObserver outside of Prefs.

chrome/browser/ui/sync/one_click_signin_helper_unittest.cc

Index: chrome/browser/ui/sync/one_click_signin_helper_unittest.cc
diff --git a/chrome/browser/ui/sync/one_click_signin_helper_unittest.cc b/chrome/browser/ui/sync/one_click_signin_helper_unittest.cc
index fa2090c6daaf72ee8601e34f5e950b9ccfcf469e..72d1dea372affb482310f76128b75db230615c71 100644
--- a/chrome/browser/ui/sync/one_click_signin_helper_unittest.cc
+++ b/chrome/browser/ui/sync/one_click_signin_helper_unittest.cc
@@ -63,14 +63,14 @@ class TestProfileIOData : public ProfileIOData {
     // Initialize the IO members required for these tests, but keep them on
     // this thread since we don't use a background thread here.
     google_services_username()->Init(prefs::kGoogleServicesUsername,
-                                     pref_service, NULL);
+                                     pref_service);
     reverse_autologin_enabled()->Init(prefs::kReverseAutologinEnabled,
-                                      pref_service, NULL);
+                                      pref_service);
     one_click_signin_rejected_email_list()->Init(
-        prefs::kReverseAutologinRejectedEmailList, pref_service, NULL);
+        prefs::kReverseAutologinRejectedEmailList, pref_service);
 
     google_services_username_pattern()->Init(
-        prefs::kGoogleServicesUsernamePattern, local_state, NULL);
+        prefs::kGoogleServicesUsernamePattern, local_state);
 
     set_signin_names_for_testing(new SigninNamesOnIOThread());
     SetCookieSettingsForTesting(cookie_settings);