Use leveldb_env::OpenDB() to open leveldb databases.

extensions/browser/value_store/leveldb_value_store.cc

Index: extensions/browser/value_store/leveldb_value_store.cc
diff --git a/extensions/browser/value_store/leveldb_value_store.cc b/extensions/browser/value_store/leveldb_value_store.cc
index 630eb6a06019c8759e787424e7cfef74eddec345..477bab0ca74cd7997869373de9dc8fa339910305 100644
--- a/extensions/browser/value_store/leveldb_value_store.cc
+++ b/extensions/browser/value_store/leveldb_value_store.cc
@@ -258,12 +258,10 @@ bool LeveldbValueStore::OnMemoryDump(
   dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
                   base::trace_event::MemoryAllocatorDump::kUnitsBytes, size);
 
-  // Memory is allocated from system allocator (malloc).
-  const char* system_allocator_name =
-      base::trace_event::MemoryDumpManager::GetInstance()
-          ->system_allocator_pool_name();
-  if (system_allocator_name)
-    pmd->AddSuballocation(dump->guid(), system_allocator_name);
+  // All leveldb databases are already dumped by leveldb_env::DBTracker. Add
+  // an edge to avoid double counting.
+  pmd->AddSuballocation(dump->guid(),
+                        leveldb_env::DBTracker::GetMemoryDumpName(db()));
 
   return true;
 }