Add callback list to PrefModelAssociator after sync data is loaded

chrome/browser/content_settings/host_content_settings_map_factory.cc

Index: chrome/browser/content_settings/host_content_settings_map_factory.cc
diff --git a/chrome/browser/content_settings/host_content_settings_map_factory.cc b/chrome/browser/content_settings/host_content_settings_map_factory.cc
index a96b421a0b5b60922df8ae6d707b64ec12aa304b..4eaf1c3e6447016f70ae772c818b9be0f645f542 100644
--- a/chrome/browser/content_settings/host_content_settings_map_factory.cc
+++ b/chrome/browser/content_settings/host_content_settings_map_factory.cc
@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "chrome/browser/prefs/pref_service_syncable_util.h"
 #include "chrome/browser/profiles/off_the_record_profile_impl.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
@@ -72,6 +73,14 @@ scoped_refptr<RefcountedKeyedService>
       profile->GetProfileType() == Profile::INCOGNITO_PROFILE,
       profile->GetProfileType() == Profile::GUEST_PROFILE));
 
+// TODO(lshang): Make this not a comment when we change scoping type and hook up
+// the migration code.
+/*  syncable_prefs::PrefServiceSyncable* pref_service =
+      PrefServiceSyncableFromProfile(profile);
+  if (pref_service)
+    pref_service->RegisterMergeDataFinishedCallback(base::Bind(
+        &HostContentSettingsMap::MigrateDomainScopedSettings, settings_map));*/
+
 #if defined(ENABLE_EXTENSIONS)
   ExtensionService *ext_service =
       extensions::ExtensionSystem::Get(profile)->extension_service();