Discard unused AppListPrefs code.

chrome/browser/ui/app_list/app_list_syncable_service.cc

Index: chrome/browser/ui/app_list/app_list_syncable_service.cc
diff --git a/chrome/browser/ui/app_list/app_list_syncable_service.cc b/chrome/browser/ui/app_list/app_list_syncable_service.cc
index b6b654289f736dbc73d40a17559de2539d991a5c..f7dd4d5f3854935f6c59c8c5ac09d99c802d0088 100644
--- a/chrome/browser/ui/app_list/app_list_syncable_service.cc
+++ b/chrome/browser/ui/app_list/app_list_syncable_service.cc
@@ -15,11 +15,9 @@
 #include "chrome/browser/apps/drive/drive_app_provider.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
-#include "chrome/browser/ui/app_list/app_list_prefs.h"
 #include "chrome/browser/ui/app_list/app_list_service.h"
 #include "chrome/browser/ui/app_list/extension_app_item.h"
 #include "chrome/browser/ui/app_list/extension_app_model_builder.h"
-#include "chrome/browser/ui/app_list/model_pref_updater.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/grit/generated_resources.h"
@@ -276,7 +274,6 @@ AppListSyncableService::AppListSyncableService(
 AppListSyncableService::~AppListSyncableService() {
   // Remove observers.
   model_observer_.reset();
-  model_pref_updater_.reset();
 }
 
 void AppListSyncableService::BuildModel() {
@@ -310,9 +307,6 @@ void AppListSyncableService::BuildModel() {
 #endif
   }
 
-  model_pref_updater_.reset(
-      new ModelPrefUpdater(AppListPrefs::Get(profile_), model_.get()));
-
   if (app_list::switches::IsDriveAppsInAppListEnabled())
     drive_app_provider_.reset(new DriveAppProvider(profile_, this));
 }