Refactor build target for sync

sync/sync_proto.gypi

Index: sync/sync_proto.gypi
diff --git a/sync/sync_proto.gypi b/sync/sync_proto.gypi
deleted file mode 100644
index fd002bf3a9460c46948133e5873cc7158051b7fc..0000000000000000000000000000000000000000
--- a/sync/sync_proto.gypi
+++ /dev/null
@@ -1,64 +0,0 @@
-# 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.
-
-{
-  'include_dirs': [
-    '..',
-  ],
-  'defines': [
-    'SYNC_IMPLEMENTATION',
-  ],
-  'sources': [
-    # NOTE: If you add a file to this list, also add it to
-    # sync/protocol/BUILD.gn
-    'protocol/app_notification_specifics.proto',
-    'protocol/app_setting_specifics.proto',
-    'protocol/app_specifics.proto',
-    'protocol/app_list_specifics.proto',
-    'protocol/article_specifics.proto',
-    'protocol/attachments.proto',
-    'protocol/autofill_specifics.proto',
-    'protocol/bookmark_specifics.proto',
-    'protocol/client_commands.proto',
-    'protocol/client_debug_info.proto',
-    'protocol/device_info_specifics.proto',
-    'protocol/dictionary_specifics.proto',
-    'protocol/encryption.proto',
-    'protocol/experiments_specifics.proto',
-    'protocol/extension_setting_specifics.proto',
-    'protocol/extension_specifics.proto',
-    'protocol/favicon_image_specifics.proto',
-    'protocol/favicon_tracking_specifics.proto',
-    'protocol/get_updates_caller_info.proto',
-    'protocol/history_delete_directive_specifics.proto',
-    'protocol/nigori_specifics.proto',
-    'protocol/managed_user_setting_specifics.proto',
-    'protocol/managed_user_shared_setting_specifics.proto',
-    'protocol/managed_user_specifics.proto',
-    'protocol/password_specifics.proto',
-    'protocol/preference_specifics.proto',
-    'protocol/priority_preference_specifics.proto',
-    'protocol/search_engine_specifics.proto',
-    'protocol/session_specifics.proto',
-    'protocol/sync.proto',
-    'protocol/sync_enums.proto',
-    'protocol/synced_notification_app_info_specifics.proto',
-    'protocol/synced_notification_data.proto',
-    'protocol/synced_notification_render.proto',
-    'protocol/synced_notification_specifics.proto',
-    'protocol/test.proto',
-    'protocol/theme_specifics.proto',
-    'protocol/typed_url_specifics.proto',
-    'protocol/unique_position.proto',
-  ],
-  'variables': {
-    'proto_in_dir': './protocol',
-    'proto_out_dir': 'sync/protocol',
-    'cc_generator_options': 'dllexport_decl=SYNC_EXPORT:',
-    'cc_include': 'sync/base/sync_export.h',
-  },
-  'includes': [
-    '../build/protoc.gypi'
-  ],
-}