Propagate more information about ValueStore errors to callers, notably an

chrome/browser/value_store/value_store_util.h

+// Copyright 2013 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 CHROME_BROWSER_VALUE_STORE_VALUE_STORE_UTIL_H_
+#define CHROME_BROWSER_VALUE_STORE_VALUE_STORE_UTIL_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/value_store/value_store.h"
+
+namespace value_store_util {
+
+// Returns a copy of |key| as a scoped_ptr. Useful for creating keys for
+// ValueStore::Error.
+scoped_ptr<std::string> NewKey(const std::string& key);
+
+// Returns an empty scoped_ptr. Useful for creating empty keys for
+// ValueStore::Error.
+scoped_ptr<std::string> NoKey();
+
+// Return an empty Error. Useful for creating ValueStore::Error-less
+// ValueStore::Read/WriteResults.
+scoped_ptr<ValueStore::Error> NoError();
+
+}  // namespace value_store_util
+
+#endif  // CHROME_BROWSER_VALUE_STORE_VALUE_STORE_UTIL_H_