Require explicit selection of traits for LazyInstance

components/sync/model_impl/model_type_store_backend.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_SYNC_MODEL_IMPL_MODEL_TYPE_STORE_BACKEND_H_
 #define COMPONENTS_SYNC_MODEL_IMPL_MODEL_TYPE_STORE_BACKEND_H_
 
 #include <memory>
 #include <string>
 #include <unordered_map>
@@ skipping 133 matching lines @@
   std::unique_ptr<leveldb::Env> env_;
 
   std::unique_ptr<leveldb::DB> db_;
 
   std::string path_;
 
   // backend_map_ holds raw pointer of backend, and when stores ask for backend,
   // GetOrCreateBackend will return scoped_refptr of backend. backend_map_
   // doesn't take reference to backend, therefore doesn't block backend
   // destruction.
-  static base::LazyInstance<BackendMap> backend_map_;
+  static base::LazyInstance<BackendMap>::DestructorAtExit backend_map_;
 
   // Macro wrapped mutex to guard against concurrent calls in debug builds.
   DFAKE_MUTEX(push_pop_);
 
   DISALLOW_COPY_AND_ASSIGN(ModelTypeStoreBackend);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_MODEL_IMPL_MODEL_TYPE_STORE_BACKEND_H_