Put column family information in LiveFileMetaData

Summary: As summary

Test Plan: compiles :)

Reviewers: dhruba, haobo, sdong, yhchiang

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D18405

include/rocksdb/db.h

@@ -54,7 +54,8 @@ class Env;
 
 // Metadata associated with each SST file.
 struct LiveFileMetaData {
-  std::string name;        // Name of the file
+  std::string column_family_name;  // Name of the column family
+  std::string name;                // Name of the file
   int level;               // Level at which this file resides.
   size_t size;             // File size in bytes.
   std::string smallestkey; // Smallest user defined key in the file.