[Sync] Move GenerateSyncableHash to base.

components/sync/base/hash_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_SYNC_BASE_HASH_UTIL_H_
+#define COMPONENTS_SYNC_BASE_HASH_UTIL_H_
+
+#include <string>
+
+#include "components/sync/base/model_type.h"
+
+namespace syncer {
+
+// Generates a fixed-length tag for the given string under the given model_type.
+std::string GenerateSyncableHash(ModelType model_type,
+                                 const std::string& client_tag);
+
+// A helper for generating the bookmark type's tag.  This is required in more
+// than one place, so we define the algorithm here to make sure the
+// implementation is consistent.
+std::string GenerateSyncableBookmarkHash(
+    const std::string& originator_cache_guid,
+    const std::string& originator_client_item_id);
+
+}  // namespace syncer
+
+#endif  // COMPONENTS_SYNC_BASE_HASH_UTIL_H_