Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/ui/webui/extensions/extension_settings_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/extensions/extension_settings_handler.h"
 
 #include "base/auto_reset.h"
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 426 matching lines @@
       source_profile = content::Source<Profile>(source).ptr();
       if (!profile->IsSameProfile(source_profile))
           return;
       MaybeUpdateAfterNotification();
       break;
     case chrome::NOTIFICATION_EXTENSION_LOADED:
     case chrome::NOTIFICATION_EXTENSION_UNLOADED:
     case chrome::NOTIFICATION_EXTENSION_UPDATE_DISABLED:
     case chrome::NOTIFICATION_EXTENSION_WARNING_CHANGED:
     case chrome::NOTIFICATION_EXTENSION_BROWSER_ACTION_VISIBILITY_CHANGED:
-    case chrome::NOTIFICATION_PREF_CHANGED:
       MaybeUpdateAfterNotification();
       break;
     default:
       NOTREACHED();
   }
 }
 
+void ExtensionSettingsHandler::OnPreferenceChanged(
+    PrefServiceBase* service,
+    const std::string& pref_name) {
+  MaybeUpdateAfterNotification();
+}
+
 void ExtensionSettingsHandler::ExtensionUninstallAccepted() {
   DCHECK(!extension_id_prompting_.empty());
 
   bool was_terminated = false;
 
   // The extension can be uninstalled in another window while the UI was
   // showing. Do nothing in that case.
   const Extension* extension =
       extension_service_->GetExtensionById(extension_id_prompting_, true);
   if (!extension) {
@@ skipping 489 matching lines @@
     std::vector<std::string> requirement_errors) {
   if (requirement_errors.empty()) {
     extension_service_->EnableExtension(extension_id);
   } else {
     ExtensionErrorReporter::GetInstance()->ReportError(
         UTF8ToUTF16(JoinString(requirement_errors, ' ')),
         true /* be noisy */);
   }
   requirements_checker_.reset();
 }