Protector adds the default prepopulated engine if it was removed.

chrome/browser/search_engines/template_url_prepopulate_data.h

Index: chrome/browser/search_engines/template_url_prepopulate_data.h
diff --git a/chrome/browser/search_engines/template_url_prepopulate_data.h b/chrome/browser/search_engines/template_url_prepopulate_data.h
index 9f141600e992d2b4de762d2c5ca998b19c58c612..80a5001fbf3f5e9c71b911ffe2f2d16e58225e19 100644
--- a/chrome/browser/search_engines/template_url_prepopulate_data.h
+++ b/chrome/browser/search_engines/template_url_prepopulate_data.h
@@ -35,6 +35,7 @@ void GetPrepopulatedEngines(PrefService* prefs,
 
 // Returns the default search provider specified by the prepopulate data.
 // The caller owns the returned value, which may be NULL.
+// If |prefs| is NULL, search provider overrides from preferences are not used.
 TemplateURL* GetPrepopulatedDefaultSearch(PrefService* prefs);
 
 // Returns a TemplateURL from the prepopulated data which has the same origin