[Sync] Move //sync to //components/sync.

sync/internal_api/attachments/proto/attachment_store.proto

-// 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.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-option retain_unknown_fields = true;
-
-package attachment_store_pb;
-
-// Metadata for leveldb attachment store database.
-message StoreMetadata {
-  // |schema_version| indicates format in which data is written in attachment
-  // store. Needed for upgrade and to prevent newer data from being loaded by
-  // older code that doesn't understand it.
-  optional int32 schema_version = 1;
-}
-
-// Metadata for attachment in attachment store. Storing metadata in separate
-// record from actual data allows us to enumerate attachments in the store
-// without incurring cost to read actual data. It also allows us to update
-// attachment metadata independent of the data.
-message RecordMetadata {
-  // Size of attachment data. Useful for attachment store space management.
-  optional int64 attachment_size = 1;
-  // Crc32c of attachment data.
-  optional fixed32 crc32c = 2;
-
-  // Component enum mirrors values of AttachmentStore::Component.
-  enum Component {
-    UNKNOWN = 0;
-    MODEL_TYPE = 1;
-    SYNC = 2;
-  }
-  // Set of components that reference this attachment.
-  repeated Component component = 3;
-}