Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/webui/ntp/app_launcher_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/ntp/app_launcher_handler.h"
 
 #include <string>
 #include <vector>
 
 #include "base/auto_reset.h"
@@ skipping 294 matching lines @@
         HandleGetApps(NULL);
       }
       break;
     }
     // The promo may not load until a couple seconds after the first NTP view,
     // so we listen for the load notification and notify the NTP when ready.
     case chrome::NOTIFICATION_WEB_STORE_PROMO_LOADED:
       // TODO(estade): Try to get rid of this inefficient operation.
       HandleGetApps(NULL);
       break;
-    case chrome::NOTIFICATION_PREF_CHANGED: {
-      DictionaryValue dictionary;
-      FillAppDictionary(&dictionary);
-      web_ui()->CallJavascriptFunction("ntp.appsPrefChangeCallback",
-                                       dictionary);
-      break;
-    }
     case chrome::NOTIFICATION_EXTENSION_INSTALL_ERROR: {
       CrxInstaller* crx_installer = content::Source<CrxInstaller>(source).ptr();
       if (!Profile::FromWebUI(web_ui())->IsSameProfile(
               crx_installer->profile())) {
         return;
       }
       // Fall through.
     }
     case chrome::NOTIFICATION_EXTENSION_LOAD_ERROR: {
       attempted_bookmark_app_install_ = false;
       break;
     }
     default:
       NOTREACHED();
   }
 }
 
+void AppLauncherHandler::OnPreferenceChanged(PrefServiceBase* service,
+                                             const std::string& pref_name) {
+  DictionaryValue dictionary;
+  FillAppDictionary(&dictionary);
+  web_ui()->CallJavascriptFunction("ntp.appsPrefChangeCallback",
+                                   dictionary);
+}
+
 void AppLauncherHandler::FillAppDictionary(DictionaryValue* dictionary) {
   // CreateAppInfo and ClearOrdinals can change the extension prefs.
   AutoReset<bool> auto_reset(&ignore_changes_, true);
 
   ListValue* list = new ListValue();
 
   for (std::set<std::string>::iterator it = visible_apps_.begin();
        it != visible_apps_.end(); ++it) {
     const Extension* extension = extension_service_->GetInstalledExtension(*it);
     if (extension && extension->ShouldDisplayInLauncher()) {
@@ skipping 571 matching lines @@
   return extension_uninstall_dialog_.get();
 }
 
 ExtensionInstallPrompt* AppLauncherHandler::GetExtensionInstallPrompt() {
   if (!extension_install_ui_.get()) {
     extension_install_ui_.reset(
         new ExtensionInstallPrompt(web_ui()->GetWebContents()));
   }
   return extension_install_ui_.get();
 }