follow the API of RamCache's same method.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24031 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/CachePlugins/DistributedRamCache.py

@@ -148,4 +148,4 @@ class DistributedRamCache(BaseCache):
 
   def getCachePluginTotalMemorySize(self):
     """ Calculate total RAM memory size of cache plugin. """
-    return 0    
+    return 0, {}