diff --git a/common/prefs.h b/common/prefs.h
index 3fc1d89..d6ef668 100644
--- a/common/prefs.h
+++ b/common/prefs.h
@@ -74,6 +74,8 @@
 
   bool Exists(const std::string& key) const override;
   bool Delete(const std::string& key) override;
+  bool Delete(const std::string& pref_key,
+              const std::vector<std::string>& nss) override;
 
   bool GetSubKeys(const std::string& ns,
                   std::vector<std::string>* keys) const override;