Delete and try to recreate localstorage database on invalid schema version.

components/leveldb/public/interfaces/leveldb.mojom

 // 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.
 
 module leveldb.mojom;
 
 import "components/filesystem/public/interfaces/directory.mojom";
 import "mojo/common/unguessable_token.mojom";
 
 enum DatabaseError {
@@ skipping 53 matching lines @@
 interface LevelDBService {
   Open(filesystem.mojom.Directory directory,
        string dbname,
        LevelDBDatabase& database) => (DatabaseError status);
   OpenWithOptions(OpenOptions options,
                   filesystem.mojom.Directory directory,
                   string dbname,
                   LevelDBDatabase& database) => (DatabaseError status);
 
   OpenInMemory(LevelDBDatabase& database) => (DatabaseError status);
+
+  Destroy(filesystem.mojom.Directory directory,
+       string dbname) => (DatabaseError status);

[jam, 2017/01/12 17:24:42]

nit: indentation

also please add documentation to this method. we should have had some on the few
before but maybe skipped because it seemed obvious. 

[Marijn Kruisselbrink, 2017/01/13 19:25:11]

Fixed, also added (minimal) documentation to the various Open methods.

 };
 
 // A leveldb database.
 interface LevelDBDatabase {
   // Basic Interface -------------------------------------------------------
 
   // Sets the database entry for "key" to "value". Returns OK on success.
   Put(array<uint8> key, array<uint8> value) => (DatabaseError status);
 
   // Remove the database entry (if any) for "key".  Returns OK on
@@ skipping 52 matching lines @@
   // Moves forward or backwards in iterator space.
   [Sync]
   IteratorNext(mojo.common.mojom.UnguessableToken iterator)
       => (bool valid, DatabaseError status, array<uint8>? key,
           array<uint8>? value);
   [Sync]
   IteratorPrev(mojo.common.mojom.UnguessableToken iterator)
       => (bool valid, DatabaseError status, array<uint8>? key,
           array<uint8>? value);
 };