[Sync] Create new top-level sync/ directory

chrome/browser/sync/protocol/extension_specifics.proto

-// Copyright (c) 2012 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.
-//
-// Sync protocol datatype extension for extensions.
-
-// Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
-// any fields in this file.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-option retain_unknown_fields = true;
-
-package sync_pb;
-
-// Properties of extension sync objects.
-//
-// Merge policy: the settings for the higher version number win; in
-// the case of a tie, server wins.
-message ExtensionSpecifics {
-  // Globally unique id for this extension.
-  optional string id = 1;
-  // The known installed version.
-  optional string version = 2;
-
-  // Auto-update URL to use for this extension.  May be blank, in
-  // which case the default one (i.e., the one for the Chrome
-  // Extensions Gallery) is used.
-  optional string update_url = 3;
-  // Whether or not this extension is enabled.
-  optional bool enabled = 4;
-  // Whether or not this extension is enabled in incognito mode.
-  optional bool incognito_enabled = 5;
-
-  // The name of the extension.  Used only for debugging.
-  optional string name = 6;
-}
-