sync: Add DeviceInfo protobuf and supporting code

sync/protocol/sync_enums.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 for communication between sync client and server.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
@@ skipping 78 matching lines @@
     UPGRADE_CLIENT              = 0; // Upgrade the client to latest version.
     CLEAR_USER_DATA_AND_RESYNC  = 1; // Clear user data from dashboard and
                                      // setup sync again.
     ENABLE_SYNC_ON_ACCOUNT      = 2; // The administrator needs to enable sync
                                      // on the account.
     STOP_AND_RESTART_SYNC       = 3; // Stop sync and set up sync again.
     DISABLE_SYNC_ON_CLIENT      = 4; // Wipe the client of all sync data and
                                      // stop syncing.
     UNKNOWN_ACTION              = 5; // This is the default.
   }
+
+  enum DeviceType {
+    TYPE_WIN = 1;
+    TYPE_MAC = 2;
+    TYPE_LINUX = 3;
+    TYPE_CROS = 4;
+    TYPE_OTHER = 5;
+    TYPE_PHONE = 6;
+    TYPE_TABLET = 7;
+  }
 }