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

third_party/leveldatabase/env_chromium.h

Index: third_party/leveldatabase/env_chromium.h
diff --git a/third_party/leveldatabase/env_chromium.h b/third_party/leveldatabase/env_chromium.h
index 690a032ad763cd96946e633de5145322bff4a592..02a68c6416ececa46669a493d7e69fed47e2227f 100644
--- a/third_party/leveldatabase/env_chromium.h
+++ b/third_party/leveldatabase/env_chromium.h
@@ -242,6 +242,13 @@ class DBTracker {
   // DBTracker singleton instance.
   static DBTracker* GetInstance();
 
+  // Returns name of memory-infra dump for |tracked_db|. Can be used to attach
+  // additional info to the database dump, or to properly attribute memory
+  // usage in memory dump providers that also dump |tracked_db|.
+  // Note that |tracked_db| should be a live database instance produced by
+  // OpenDatabase() method or leveldb_env::OpenDB() function.
+  static std::string GetMemoryDumpName(leveldb::DB* tracked_db);
+
   // Provides extra information about a tracked database.
   class TrackedDB : public leveldb::DB {
    public:
@@ -252,6 +259,8 @@ class DBTracker {
   // Opens a database and starts tracking it. As long as the opened database
   // is alive (i.e. its instance is not destroyed) the database is exposed to
   // memory-infra and is enumerated by VisitDatabases() method.
+  // This function is an implementation detail of leveldb_env::OpenDB(), and
+  // has similar guarantees regarding |dbptr| argument.
   leveldb::Status OpenDatabase(const leveldb::Options& options,
                                const std::string& name,
                                TrackedDB** dbptr);
@@ -285,7 +294,9 @@ class DBTracker {
 };
 
 // Opens a database and exposes it to Chrome's tracing (see DBTracker for
-// details). Note that |dbptr| is touched only when function succeeds.
+// details). The function guarantees that:
+//   1. |dbptr| is not touched on failure
+//   2. |dbptr| is not NULL on success
 leveldb::Status OpenDB(const leveldb::Options& options,
                        const std::string& name,
                        std::unique_ptr<leveldb::DB>* dbptr);