mojo leveldb: Add an iteration interface.

components/leveldb/public/cpp/util.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 COMPONENTS_LEVELDB_PUBLIC_CPP_UTIL_H_
+#define COMPONENTS_LEVELDB_PUBLIC_CPP_UTIL_H_
+
+#include "components/leveldb/public/interfaces/leveldb.mojom.h"
+
+namespace leveldb {
+
+class Slice;
+class Status;
+
+// Builds a mojo DatabaseError from a leveldb::Status object.
+DatabaseError LeveldbStatusToError(const leveldb::Status& s);
+
+// Creates a leveldb Status object form a database error and two optional
+// messages. A mojoification of the various static leveldb::Status
+// constructors.
+leveldb::Status DatabaseErrorToStatus(DatabaseError e,
+                                      const Slice& msg,
+                                      const Slice& msg2);
+
+// Builds a Slice pointing to the data inside |a|. This is not a type-converter
+// as it is not a copy operation; the returned Slice points into |a| and must
+// outlive |a|.
+leveldb::Slice GetSliceFor(const mojo::Array<uint8_t>& a);
+
+// Copies the data that |s| points to into a mojo::Array.
+mojo::Array<uint8_t> GetArrayFor(const leveldb::Slice& s);
+
+}  // namespace leveldb
+
+#endif  // COMPONENTS_LEVELDB_PUBLIC_CPP_UTIL_H_