Cleanup property-related variable names

Summary:
I noticed these names were quite confusing while updating GetProperty
documentation.

Test Plan: running "make commit-prereq -j32"

Reviewers: yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D53073

db/internal_stats.cc

@@ -99,9 +99,8 @@ static const std::string compaction_pending = "compaction-pending";
 static const std::string background_errors = "background-errors";
 static const std::string cur_size_active_mem_table =
                           "cur-size-active-mem-table";
-static const std::string cur_size_unflushed_mem_tables =
-    "cur-size-all-mem-tables";
-static const std::string cur_size_all_mem_tables = "size-all-mem-tables";
+static const std::string cur_size_all_mem_tables = "cur-size-all-mem-tables";
+static const std::string size_all_mem_tables = "size-all-mem-tables";
 static const std::string num_entries_active_mem_table =
                           "num-entries-active-mem-table";
 static const std::string num_entries_imm_mem_tables =
@@ -154,9 +153,9 @@ const std::string DB::Properties::kBackgroundErrors =
 const std::string DB::Properties::kCurSizeActiveMemTable =
                       rocksdb_prefix + cur_size_active_mem_table;
 const std::string DB::Properties::kCurSizeAllMemTables =
-    rocksdb_prefix + cur_size_unflushed_mem_tables;
-const std::string DB::Properties::kSizeAllMemTables =
     rocksdb_prefix + cur_size_all_mem_tables;
+const std::string DB::Properties::kSizeAllMemTables =
+    rocksdb_prefix + size_all_mem_tables;
 const std::string DB::Properties::kNumEntriesActiveMemTable =
                       rocksdb_prefix + num_entries_active_mem_table;
 const std::string DB::Properties::kNumEntriesImmMemTables =
@@ -232,9 +231,9 @@ DBPropertyType GetPropertyType(const Slice& property, bool* is_int_property,
     return kBackgroundErrors;
   } else if (in == cur_size_active_mem_table) {
     return kCurSizeActiveMemTable;
-  } else if (in == cur_size_unflushed_mem_tables) {
-    return kCurSizeAllMemTables;
   } else if (in == cur_size_all_mem_tables) {
+    return kCurSizeAllMemTables;
+  } else if (in == size_all_mem_tables) {
     return kSizeAllMemTables;
   } else if (in == num_entries_active_mem_table) {
     return kNumEntriesInMutableMemtable;