Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/webui/options/content_settings_handler.cc

Index: chrome/browser/ui/webui/options/content_settings_handler.cc
diff --git a/chrome/browser/ui/webui/options/content_settings_handler.cc b/chrome/browser/ui/webui/options/content_settings_handler.cc
index c8ad7a67e35e38b93514066e76a6b1261352e4de..f2565aa1442bb7297c7d5a786f013dc5fb8dfbcf 100644
--- a/chrome/browser/ui/webui/options/content_settings_handler.cc
+++ b/chrome/browser/ui/webui/options/content_settings_handler.cc
@@ -540,17 +540,6 @@ void ContentSettingsHandler::Observe(
       break;
     }
 
-    case chrome::NOTIFICATION_PREF_CHANGED: {
-      const std::string& pref_name =
-          *content::Details<std::string>(details).ptr();
-      if (pref_name == prefs::kGeolocationContentSettings)
-        UpdateGeolocationExceptionsView();
-      else if (pref_name == prefs::kPepperFlashSettingsEnabled)
-        RefreshFlashSettingsCache(false);
-
-      break;
-    }
-
     case chrome::NOTIFICATION_DESKTOP_NOTIFICATION_SETTINGS_CHANGED: {
       UpdateNotificationExceptionsView();
       break;
@@ -566,6 +555,14 @@ void ContentSettingsHandler::Observe(
   }
 }
 
+void ContentSettingsHandler::OnPreferenceChanged(PrefServiceBase* service,
+                                                 const std::string& pref_name) {
+  if (pref_name == prefs::kGeolocationContentSettings)
+    UpdateGeolocationExceptionsView();
+  else if (pref_name == prefs::kPepperFlashSettingsEnabled)
+    RefreshFlashSettingsCache(false);
+}
+
 void ContentSettingsHandler::OnGetPermissionSettingsCompleted(
     uint32 request_id,
     bool success,