leveldb: Use base::RepeatingCallback in DBTracker.

third_party/leveldatabase/env_chromium.h

 // Copyright (c) 2013 The LevelDB Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
 #ifndef THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_
 #define THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_
 
 #include <deque>
 #include <functional>

[pwnall, 2017/07/06 00:49:08]

Do we still need <functional> now that we don't use std::function?

 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/containers/linked_list.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/metrics/histogram.h"
 #include "leveldb/db.h"
 #include "leveldb/env.h"
 #include "port/port_chromium.h"
 #include "util/mutexlock.h"
 
@@ skipping 224 matching lines @@
     virtual const std::string& name() const = 0;
   };
 
   // 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.
   leveldb::Status OpenDatabase(const leveldb::Options& options,
                                const std::string& name,
                                TrackedDB** dbptr);
 
-  using DatabaseVisitor = std::function<void(TrackedDB*)>;
+  using DatabaseVisitor = base::RepeatingCallback<void(TrackedDB*)>;
 
   // Calls |visitor| for each live database. The database is live from the
   // point it was returned from OpenDatabase() and up until its instance is
   // destroyed.
   // The databases may be visited in an arbitrary order.
   // This function takes a lock, preventing any database from being opened or
   // destroyed (but doesn't lock the databases themselves).
   void VisitDatabases(const DatabaseVisitor& visitor);
 
  private:
@@ skipping 16 matching lines @@
 
 // Opens a database and exposes it to Chrome's tracing (see DBTracker for
 // details). Note that |dbptr| is touched only when function succeeds.
 leveldb::Status OpenDB(const leveldb::Options& options,
                        const std::string& name,
                        std::unique_ptr<leveldb::DB>* dbptr);
 
 }  // namespace leveldb_env
 
 #endif  // THIRD_PARTY_LEVELDATABASE_ENV_CHROMIUM_H_