Add ManagedUserSettings Sync data type.

sync/internal_api/base_node.cc

Index: sync/internal_api/base_node.cc
diff --git a/sync/internal_api/base_node.cc b/sync/internal_api/base_node.cc
index b45787fbcf69f543e2b9ce61a2a46d8a1a70f46d..3da3a73c1c814f9c69c1c6b7d5c438d8b902bc68 100644
--- a/sync/internal_api/base_node.cc
+++ b/sync/internal_api/base_node.cc
@@ -329,6 +329,12 @@ const sync_pb::SessionSpecifics& BaseNode::GetSessionSpecifics() const {
   return GetEntitySpecifics().session();
 }
 
+const sync_pb::ManagedUserSettingSpecifics&
+    BaseNode::GetManagedUserSettingSpecifics() const {
+  DCHECK_EQ(GetModelType(), MANAGED_USER_SETTINGS);
+  return GetEntitySpecifics().managed_user_setting();
+}
+
 const sync_pb::DeviceInfoSpecifics& BaseNode::GetDeviceInfoSpecifics() const {
   DCHECK_EQ(GetModelType(), DEVICE_INFO);
   return GetEntitySpecifics().device_info();