Remove NOTIFICATION_SYSTEM_SETTING_CHANGED, switch CrosSettings to base::CallbackRegistry.

chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc

Index: chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
diff --git a/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc b/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
index 7ef79d1255778914daa0d6f57006eb8b9f578af0..cfd738a90322420e9c6f48f5689ab220bc23347d 100644
--- a/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
+++ b/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
@@ -167,7 +167,16 @@ void CoreChromeOSOptionsHandler::ObservePref(const std::string& pref_name) {
   }
   if (!CrosSettings::IsCrosSettings(pref_name))
     return ::options::CoreOptionsHandler::ObservePref(pref_name);
-  CrosSettings::Get()->AddSettingsObserver(pref_name.c_str(), this);
+
+  scoped_ptr<CrosSettings::ObserverSubscription> subscription =
+      CrosSettings::Get()->AddSettingsObserver(
+          pref_name.c_str(),
+          base::Bind(&CoreChromeOSOptionsHandler::NotifySettingsChanged,
+                     base::Unretained(this),
+                     pref_name));
+  linked_ptr<CrosSettings::ObserverSubscription> subscription_linked(
+      subscription.release());

[Mattias Nissler (ping if slow), 2013/09/18 09:09:48]

Shouldn't you be able to just declare |subscription| a linked_ptr if you add a
.release() on the return value of AddSettingsObserver?

[Avi (use Gerrit), 2013/09/18 16:41:44]

Done.

+  pref_subscription_map_.insert(make_pair(pref_name, subscription_linked));
 }
 
 void CoreChromeOSOptionsHandler::SetPref(const std::string& pref_name,
@@ -195,7 +204,7 @@ void CoreChromeOSOptionsHandler::StopObservingPref(const std::string& path) {
     return;  // We unregister those in the destructor.
   // Unregister this instance from observing prefs of chrome os settings.
   if (CrosSettings::IsCrosSettings(path))
-    CrosSettings::Get()->RemoveSettingsObserver(path.c_str(), this);
+    pref_subscription_map_.erase(path);
   else  // Call base class to handle regular preferences.
     ::options::CoreOptionsHandler::StopObservingPref(path);
 }
@@ -208,17 +217,6 @@ void CoreChromeOSOptionsHandler::GetLocalizedValues(
   AddAccountUITweaksLocalizedValues(localized_strings);
 }
 
-void CoreChromeOSOptionsHandler::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  if (type == chrome::NOTIFICATION_SYSTEM_SETTING_CHANGED) {
-    NotifySettingsChanged(content::Details<std::string>(details).ptr());
-    return;
-  }
-  ::options::CoreOptionsHandler::Observe(type, source, details);
-}
-
 void CoreChromeOSOptionsHandler::SelectNetworkCallback(
     const base::ListValue* args) {
   std::string service_path;
@@ -252,12 +250,12 @@ void CoreChromeOSOptionsHandler::OnPreferenceChanged(
 }
 
 void CoreChromeOSOptionsHandler::NotifySettingsChanged(
-    const std::string* setting_name) {
-  DCHECK(CrosSettings::Get()->IsCrosSettings(*setting_name));
-  scoped_ptr<base::Value> value(FetchPref(*setting_name));
+    const std::string& setting_name) {
+  DCHECK(CrosSettings::Get()->IsCrosSettings(setting_name));
+  scoped_ptr<base::Value> value(FetchPref(setting_name));
   if (!value.get())
     NOTREACHED();
-  DispatchPrefChangeNotification(*setting_name, value.Pass());
+  DispatchPrefChangeNotification(setting_name, value.Pass());
 }
 
 void CoreChromeOSOptionsHandler::NotifyProxyPrefsChanged() {