app_sorting() calls should go via ExtensionSystem intsead of prefs.

chrome/browser/extensions/install_tracker.cc

 // Copyright 2013 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/extensions/install_tracker.h"
 
 #include "base/bind.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/install_tracker_factory.h"
 #include "content/public/browser/notification_service.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extension_system.h"
 #include "extensions/browser/pref_names.h"
 
 namespace extensions {
 
 InstallTracker::InstallTracker(content::BrowserContext* browser_context,
                                extensions::ExtensionPrefs* prefs)
     : extension_registry_observer_(this) {
   registrar_.Add(this,
                  extensions::NOTIFICATION_EXTENSION_UPDATE_DISABLED,
                  content::Source<content::BrowserContext>(browser_context));
   extension_registry_observer_.Add(ExtensionRegistry::Get(browser_context));
 
   // Prefs may be null in tests.
   if (prefs) {
-    AppSorting* sorting = prefs->app_sorting();
+    AppSorting* sorting = ExtensionSystem::Get(browser_context)->app_sorting();
     registrar_.Add(this,
                    chrome::NOTIFICATION_APP_LAUNCHER_REORDERED,
                    content::Source<AppSorting>(sorting));
     pref_change_registrar_.Init(prefs->pref_service());
     pref_change_registrar_.Add(
         pref_names::kExtensions,
         base::Bind(&InstallTracker::OnAppsReordered, base::Unretained(this)));
   }
 }
 
@@ skipping 114 matching lines @@
     const Extension* extension,
     bool is_update) {
   RemoveActiveInstall(extension->id());
 }
 
 void InstallTracker::OnAppsReordered() {
   FOR_EACH_OBSERVER(InstallObserver, observers_, OnAppsReordered());
 }
 
 }  // namespace extensions