Revert of This CL replaces e-mail with AccountId on user selection screen.

components/user_manager/user_manager_base.h

Index: components/user_manager/user_manager_base.h
diff --git a/components/user_manager/user_manager_base.h b/components/user_manager/user_manager_base.h
index dd46c5d7d0d3a61d49a52db473b4ca5b023ff69b..ead7d4497e74cb7632dd271482f2e54267584ced 100644
--- a/components/user_manager/user_manager_base.h
+++ b/components/user_manager/user_manager_base.h
@@ -154,13 +154,13 @@
   // TODO(xiyuan): Figure out a better way to expose this info.
   virtual bool HasPendingBootstrap(const AccountId& account_id) const;
 
-  // Helper function that converts users from |users_list| to |users_vector| and
+  // Helper function that copies users from |users_list| to |users_vector| and
   // |users_set|. Duplicates and users already present in |existing_users| are
   // skipped.
-  void ParseUserList(const base::ListValue& users_list,
-                     const std::set<AccountId>& existing_users,
-                     std::vector<AccountId>* users_vector,
-                     std::set<AccountId>* users_set);
+  static void ParseUserList(const base::ListValue& users_list,
+                            const std::set<AccountId>& existing_users,
+                            std::vector<AccountId>* users_vector,
+                            std::set<AccountId>* users_set);
 
   // Returns true if trusted device policies have successfully been retrieved
   // and ephemeral users are enabled.