Privatize StrongBinding lifetime management

components/leveldb/leveldb_service_impl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/leveldb/leveldb_service_impl.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "components/leveldb/env_mojo.h"
 #include "components/leveldb/leveldb_database_impl.h"
 #include "components/leveldb/public/cpp/util.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
 #include "third_party/leveldatabase/env_chromium.h"
 #include "third_party/leveldatabase/src/helpers/memenv/memenv.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 #include "third_party/leveldatabase/src/include/leveldb/env.h"
 #include "third_party/leveldatabase/src/include/leveldb/filter_policy.h"
 #include "third_party/leveldatabase/src/include/leveldb/slice.h"
 
 namespace leveldb {
 
 LevelDBServiceImpl::LevelDBServiceImpl(
@@ skipping 30 matching lines @@
   LevelDBMojoProxy::OpaqueDir* dir =
       thread_->RegisterDirectory(std::move(directory));
 
   std::unique_ptr<MojoEnv> env_mojo(new MojoEnv(thread_, dir));
   options.env = env_mojo.get();
 
   leveldb::DB* db = nullptr;
   leveldb::Status s = leveldb::DB::Open(options, dbname, &db);
 
   if (s.ok()) {
-    new LevelDBDatabaseImpl(std::move(database), std::move(env_mojo),
-                            base::WrapUnique(db));
+    mojo::MakeStrongBinding(base::MakeUnique<LevelDBDatabaseImpl>(
+                                std::move(env_mojo), base::WrapUnique(db)),
+                            std::move(database));
   }
 
   callback.Run(LeveldbStatusToError(s));
 }
 
 void LevelDBServiceImpl::OpenInMemory(
     leveldb::mojom::LevelDBDatabaseRequest database,
     const OpenCallback& callback) {
   leveldb::Options options;
   options.create_if_missing = true;
   options.max_open_files = 0;  // Use minimum.
 
   std::unique_ptr<leveldb::Env> env(
       leveldb::NewMemEnv(leveldb::Env::Default()));
   options.env = env.get();
 
   leveldb::DB* db = nullptr;
   leveldb::Status s = leveldb::DB::Open(options, "", &db);
 
   if (s.ok()) {
-    new LevelDBDatabaseImpl(std::move(database), std::move(env),
-                            base::WrapUnique(db));
+    mojo::MakeStrongBinding(base::MakeUnique<LevelDBDatabaseImpl>(
+                                std::move(env), base::WrapUnique(db)),
+                            std::move(database));
   }
 
   callback.Run(LeveldbStatusToError(s));
 }
 
 }  // namespace leveldb