[Sync] Generalize StringOrdinal to handle ordinal_in_parent field

chrome/browser/extensions/extension_prefs.cc

Index: chrome/browser/extensions/extension_prefs.cc
diff --git a/chrome/browser/extensions/extension_prefs.cc b/chrome/browser/extensions/extension_prefs.cc
index 11189f75b0e01ef270bfaf6d3a9815e2b7f0a2a8..23461840b649fad40028badb173d6571db14e034 100644
--- a/chrome/browser/extensions/extension_prefs.cc
+++ b/chrome/browser/extensions/extension_prefs.cc
@@ -1391,7 +1391,7 @@ void ExtensionPrefs::OnExtensionInstalled(
     const Extension* extension,
     Extension::State initial_state,
     bool from_webstore,
-    const StringOrdinal& page_ordinal) {
+    const syncer::StringOrdinal& page_ordinal) {
   const std::string& id = extension->id();
   CHECK(Extension::IdIsValid(id));
   ScopedExtensionPrefUpdate update(prefs_, id);
@@ -1429,7 +1429,7 @@ void ExtensionPrefs::OnExtensionInstalled(
   extension_dict->Remove(kRegisteredEvents, NULL);
 
   if (extension->is_app()) {
-    StringOrdinal new_page_ordinal = page_ordinal.IsValid() ?
+    syncer::StringOrdinal new_page_ordinal = page_ordinal.IsValid() ?
         page_ordinal : extension_sorting_->GetNaturalAppPageOrdinal();
     if (!extension_sorting_->GetPageOrdinal(id).IsValid())
       extension_sorting_->SetPageOrdinal(id, new_page_ordinal);