Remove NOTIFICATION_SYSTEM_SETTING_CHANGED, switch CrosSettings to base::CallbackRegistry.

chrome/browser/chromeos/login/login_screen_policy_browsertest.cc

Index: chrome/browser/chromeos/login/login_screen_policy_browsertest.cc
diff --git a/chrome/browser/chromeos/login/login_screen_policy_browsertest.cc b/chrome/browser/chromeos/login/login_screen_policy_browsertest.cc
index 8467736feb80f2ab41fc0a3fedb099c6b429d5d2..2829d21af8113585b63e15bc8223b3687f026e45 100644
--- a/chrome/browser/chromeos/login/login_screen_policy_browsertest.cc
+++ b/chrome/browser/chromeos/login/login_screen_policy_browsertest.cc
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
-#include "chrome/browser/chrome_notification_types.h"
+#include "base/memory/ref_counted.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/chromeos/policy/device_policy_cros_browser_test.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
@@ -11,8 +11,6 @@
 #include "chrome/browser/policy/proto/chromeos/chrome_device_policy.pb.h"
 #include "chrome/common/chrome_switches.h"
 #include "chromeos/chromeos_switches.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/test/mock_notification_observer.h"
 #include "content/public/test/test_utils.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -37,20 +35,20 @@ class LoginScreenPolicyTest : public policy::DevicePolicyCrosBrowserTest {
 IN_PROC_BROWSER_TEST_F(LoginScreenPolicyTest, DisableSupervisedUsers) {
   EXPECT_FALSE(chromeos::UserManager::Get()->AreLocallyManagedUsersAllowed());
 
-  content::WindowedNotificationObserver windowed_observer(
-       chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED,
-       content::NotificationService::AllSources());
-  chromeos::CrosSettings::Get()->AddSettingsObserver(
-      chromeos::kAccountsPrefSupervisedUsersEnabled, &windowed_observer);
+  scoped_refptr<content::MessageLoopRunner> runner(
+      new content::MessageLoopRunner);
+  scoped_ptr<CrosSettings::ObserverSubscription> subscription(
+      chromeos::CrosSettings::Get()->AddSettingsObserver(
+          chromeos::kAccountsPrefSupervisedUsersEnabled,
+          runner->QuitClosure()));
+
   em::ChromeDeviceSettingsProto& proto(device_policy()->payload());
   proto.mutable_supervised_users_settings()->set_supervised_users_enabled(true);
   RefreshDevicePolicy();
-  windowed_observer.Wait();
 
-  EXPECT_TRUE(chromeos::UserManager::Get()->AreLocallyManagedUsersAllowed());
+  runner->Run();
 
-  chromeos::CrosSettings::Get()->RemoveSettingsObserver(
-      chromeos::kAccountsPrefSupervisedUsersEnabled, &windowed_observer);
+  EXPECT_TRUE(chromeos::UserManager::Get()->AreLocallyManagedUsersAllowed());
 }
 
 }  // namespace chromeos