Added Instant preference syncing and tests.

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

Index: chrome/browser/ui/webui/ntp/app_launcher_handler.cc
diff --git a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
index e8919666bc8d72fb723baebf5c15732b9c627e8b..15e009e99870360a1ea38a357c2f5e7da0210729 100644
--- a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
+++ b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
@@ -506,6 +506,8 @@ void AppLauncherHandler::HandleGetApps(const ListValue* args) {
         Source<Profile>(profile));
     registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LAUNCHER_REORDERED,
         Source<ExtensionPrefs>(extension_service_->extension_prefs()));
+    registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LAUNCHER_REORDERED,
+        Source<ExtensionService>(extension_service_));
     registrar_.Add(this, chrome::NOTIFICATION_WEB_STORE_PROMO_LOADED,
         Source<Profile>(profile));
     registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_INSTALL_ERROR,
@@ -708,7 +710,7 @@ void AppLauncherHandler::HandleReorderApps(const ListValue* args) {
     auto_reset.reset(new AutoReset<bool>(&ignore_changes_, true));
 
   extension_service_->extension_prefs()->SetAppDraggedByUser(dragged_app_id);
-  extension_service_->extension_prefs()->SetAppLauncherOrder(extension_ids);
+  extension_service_->SetAppLauncherOrder(extension_ids);
 }
 
 void AppLauncherHandler::HandleSetPageIndex(const ListValue* args) {
@@ -722,8 +724,8 @@ void AppLauncherHandler::HandleSetPageIndex(const ListValue* args) {
   if (NewTabUI::NTP4Enabled())
     auto_reset.reset(new AutoReset<bool>(&ignore_changes_, true));
 
-  extension_service_->extension_prefs()->SetPageIndex(extension_id,
-      static_cast<int>(page_index));
+  extension_service_->SetPageIndex(extension_id,
+                                   static_cast<int32>(page_index));
 }
 
 void AppLauncherHandler::HandlePromoSeen(const ListValue* args) {