[Sync] Move attachments code out of core/.

components/sync/core_impl/attachments/proto/BUILD.gn

Index: components/sync/core_impl/attachments/proto/BUILD.gn
diff --git a/components/sync/core_impl/attachments/proto/BUILD.gn b/components/sync/core_impl/attachments/proto/BUILD.gn
deleted file mode 100644
index 6ec4b950fdbd5fbe44f1efab0e7386a918696ca0..0000000000000000000000000000000000000000
--- a/components/sync/core_impl/attachments/proto/BUILD.gn
+++ /dev/null
@@ -1,14 +0,0 @@
-# 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.
-
-import("//third_party/protobuf/proto_library.gni")
-
-proto_library("proto") {
-  # This should only get compiled into the sync component.
-  visibility = [ "//components/sync" ]
-
-  sources = [
-    "attachment_store.proto",
-  ]
-}