style: made container APIs more consistent.

Change-Id: Ib4feedfc4c9fb497dfcd67e7e6a33ee03db58d7f
refs: #4337
diff --git a/src/name-prefix-list.hpp b/src/name-prefix-list.hpp
index 5ec94ef..8351b3b 100644
--- a/src/name-prefix-list.hpp
+++ b/src/name-prefix-list.hpp
@@ -60,7 +60,7 @@
   sort();
 
   size_t
-  getSize()
+  size() const
   {
     return m_names.size();
   }