Use PrefChangeRegistrar everywhere

chrome/browser/notifications/desktop_notification_service.cc

Index: chrome/browser/notifications/desktop_notification_service.cc
diff --git a/chrome/browser/notifications/desktop_notification_service.cc b/chrome/browser/notifications/desktop_notification_service.cc
index b55c573771abc259efbf23efe582336e4029b024..1b3df09c899061a43c64599c5432270a59f819e4 100644
--- a/chrome/browser/notifications/desktop_notification_service.cc
+++ b/chrome/browser/notifications/desktop_notification_service.cc
@@ -210,6 +210,7 @@ DesktopNotificationService::DesktopNotificationService(Profile* profile,
     NotificationUIManager* ui_manager)
     : profile_(profile),
       ui_manager_(ui_manager) {
+  registrar_.Init(profile_->GetPrefs());
   InitPrefs();
   StartObserving();
 }
@@ -254,21 +255,15 @@ void DesktopNotificationService::InitPrefs() {
 
 void DesktopNotificationService::StartObserving() {
   if (!profile_->IsOffTheRecord()) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->AddPrefObserver(prefs::kDesktopNotificationDefaultContentSetting,
-                           this);
-    prefs->AddPrefObserver(prefs::kDesktopNotificationAllowedOrigins, this);
-    prefs->AddPrefObserver(prefs::kDesktopNotificationDeniedOrigins, this);
+    registrar_.Add(prefs::kDesktopNotificationDefaultContentSetting, this);
+    registrar_.Add(prefs::kDesktopNotificationAllowedOrigins, this);
+    registrar_.Add(prefs::kDesktopNotificationDeniedOrigins, this);
   }
 }
 
 void DesktopNotificationService::StopObserving() {
   if (!profile_->IsOffTheRecord()) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationDefaultContentSetting,
-                              this);
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationAllowedOrigins, this);
-    prefs->RemovePrefObserver(prefs::kDesktopNotificationDeniedOrigins, this);
+    registrar_.RemoveAll();
   }
 }