sync: Add DeviceInfo protobuf and supporting code

sync/protocol/session_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 sessions.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
@@ skipping 15 matching lines @@
   optional int32 tab_node_id = 4 [default = -1];
 }
 
 // Properties of session sync objects.
 message SessionHeader {
   // Each session is composed of windows.
   repeated SessionWindow window = 2;
   // A non-unique but human-readable name to describe this client.
   optional string client_name = 3;
   // The type of device.
-  enum DeviceType {
-    TYPE_WIN = 1;
-    TYPE_MAC = 2;
-    TYPE_LINUX = 3;
-    TYPE_CROS = 4;
-    TYPE_OTHER = 5;
-    TYPE_PHONE = 6;
-    TYPE_TABLET = 7;
-  }
-  optional DeviceType device_type = 4;
+  optional SyncEnums.DeviceType device_type = 4;
 }
 
 message SessionWindow {
   // Unique (to the owner) id for this window.
   optional int32 window_id = 1;
   // Index of the selected tab in tabs; -1 if no tab is selected.
   optional int32 selected_tab_index = 2 [default = -1];
   // Type of the browser. Currently we only store browsers of type
   // TYPE_TABBED and TYPE_POPUP.
   enum BrowserType {
@@ skipping 63 matching lines @@
   // User used the address bar to trigger this navigation.
   optional bool navigation_from_address_bar = 11;
   // User is navigating to the home page.
   optional bool navigation_home_page = 12;
   // The beginning of a navigation chain.
   optional bool navigation_chain_start = 13;
   // The last transition in a redirect chain.
   optional bool navigation_chain_end = 14;
 }