Store a version number in the localstorage database.

content/browser/dom_storage/local_storage_context_mojo.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_
 #define CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_
 
 #include <memory>
 
 #include "base/files/file_path.h"
@@ skipping 25 matching lines @@
   void SetDatabaseForTesting(leveldb::mojom::LevelDBDatabasePtr database);
 
  private:
   void OnLevelDBWrapperHasNoBindings(const url::Origin& origin);
   void OnUserServiceConnectionComplete();
   void OnUserServiceConnectionError();
 
   // Part of our asynchronous directory opening called from OpenLocalStorage().
   void OnDirectoryOpened(filesystem::mojom::FileError err);
   void OnDatabaseOpened(leveldb::mojom::DatabaseError status);
+  void OnGotDatabaseVersion(leveldb::mojom::DatabaseError status,
+                            const std::vector<uint8_t>& value);
 
   // The (possibly delayed) implementation of OpenLocalStorage(). Can be called
   // directly from that function, or through |on_database_open_callbacks_|.
   void BindLocalStorage(const url::Origin& origin,
                         mojom::LevelDBWrapperRequest request);
 
   service_manager::Connector* const connector_;
   const base::FilePath subdirectory_;
 
   enum ConnectionState {
@@ skipping 14 matching lines @@
 
   // Maps between an origin and its prefixed LevelDB view.
   std::map<url::Origin, std::unique_ptr<LevelDBWrapperImpl>> level_db_wrappers_;
 
   base::WeakPtrFactory<LocalStorageContextMojo> weak_ptr_factory_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_LOCAL_STORAGE_CONTEXT_MOJO_H_