leveldb: Add DBTracker for exposing databases to Chrome's memory-infra.

content/browser/dom_storage/session_storage_database.cc

Index: content/browser/dom_storage/session_storage_database.cc
diff --git a/content/browser/dom_storage/session_storage_database.cc b/content/browser/dom_storage/session_storage_database.cc
index 0bf1caaae7a5403c1a739f867c140737e6a2ba19..91f0f7ade21e995a1396ba18940919be4d4549be 100644
--- a/content/browser/dom_storage/session_storage_database.cc
+++ b/content/browser/dom_storage/session_storage_database.cc
@@ -447,7 +447,7 @@ leveldb::Status SessionStorageDatabase::TryToOpen(leveldb::DB** db) {
   // Default write_buffer_size is 4 MB but that might leave a 3.999
   // memory allocation in RAM from a log file recovery.
   options.write_buffer_size = 64 * 1024;
-  return leveldb::DB::Open(options, file_path_.AsUTF8Unsafe(), db);
+  return leveldb_env::DBRegistry::Open(options, file_path_.AsUTF8Unsafe(), db);
 }
 
 bool SessionStorageDatabase::IsOpen() const {