[Sync] Move attachments code out of core/.

components/sync/core/attachments/attachment_util.h

-// Copyright 2014 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_CORE_ATTACHMENTS_ATTACHMENT_UTIL_H_
-#define COMPONENTS_SYNC_CORE_ATTACHMENTS_ATTACHMENT_UTIL_H_
-
-#include <stdint.h>
-
-#include "base/memory/ref_counted.h"
-
-namespace base {
-class RefCountedMemory;
-}
-
-namespace syncer {
-
-// Return the crc32c of the memory described by |data|.
-//
-// Potentially expensive.
-// Ideally this function should be static function in Attachment class, but
-// include_rules from sync/api/DEPS don't allow direct dependency on
-// third_party.
-uint32_t ComputeCrc32c(const scoped_refptr<base::RefCountedMemory>& data);
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_CORE_ATTACHMENTS_ATTACHMENT_UTIL_H_