Use PrefChangeRegistrar everywhere

chrome/browser/cocoa/content_settings_dialog_controller.mm

Index: chrome/browser/cocoa/content_settings_dialog_controller.mm
diff --git a/chrome/browser/cocoa/content_settings_dialog_controller.mm b/chrome/browser/cocoa/content_settings_dialog_controller.mm
index 9ed20788bb73a62dfea86b28d95ad35230baa949..001a3ec33386bcae559f5b910df7c25bbea94a99 100644
--- a/chrome/browser/cocoa/content_settings_dialog_controller.mm
+++ b/chrome/browser/cocoa/content_settings_dialog_controller.mm
@@ -140,11 +140,11 @@ class PrefObserverDisabler {
     // Manually observe notifications for preferences that are grouped in
     // the HostContentSettingsMap or GeolocationContentSettingsMap.
     PrefService* prefs = profile_->GetPrefs();
-    prefs->AddPrefObserver(prefs::kBlockThirdPartyCookies, observer_.get());
-    prefs->AddPrefObserver(prefs::kBlockNonsandboxedPlugins, observer_.get());
-    prefs->AddPrefObserver(prefs::kDefaultContentSettings, observer_.get());
-    prefs->AddPrefObserver(prefs::kGeolocationDefaultContentSetting,
-                           observer_.get());
+    registrar_.Init(prefs);
+    registrar_.Add(prefs::kBlockThirdPartyCookies, observer_.get());
+    registrar_.Add(prefs::kBlockNonsandboxedPlugins, observer_.get());
+    registrar_.Add(prefs::kDefaultContentSettings, observer_.get());
+    registrar_.Add(prefs::kGeolocationDefaultContentSetting, observer_.get());
 
     // We don't need to observe changes in this value.
     lastSelectedTab_.Init(prefs::kContentSettingsWindowLastTabIndex,
@@ -153,20 +153,6 @@ class PrefObserverDisabler {
   return self;
 }
 
-- (void)dealloc {
-  if (profile_) {
-    PrefService* prefs = profile_->GetPrefs();
-    prefs->RemovePrefObserver(prefs::kBlockThirdPartyCookies, observer_.get());
-    prefs->RemovePrefObserver(prefs::kBlockNonsandboxedPlugins,
-                              observer_.get());
-    prefs->RemovePrefObserver(prefs::kDefaultContentSettings, observer_.get());
-    prefs->RemovePrefObserver(prefs::kGeolocationDefaultContentSetting,
-                              observer_.get());
-  }
-
-  [super dealloc];
-}
-
 - (void)closeExceptionsSheet {
   NSWindow* attachedSheet = [[self window] attachedSheet];
   if (attachedSheet) {