Add Sync data type for managed users.

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 1e1513b1b7bf0c2bf74b116c1783230dbfcad77c..88dec8cbd36f474241e3a21fe65cf146d50dde6c 100644
--- a/sync/internal_api/base_node.cc
+++ b/sync/internal_api/base_node.cc
@@ -335,6 +335,11 @@ const sync_pb::ManagedUserSettingSpecifics&
   return GetEntitySpecifics().managed_user_setting();
 }
 
+const sync_pb::ManagedUserSpecifics& BaseNode::GetManagedUserSpecifics() const {
+  DCHECK_EQ(GetModelType(), MANAGED_USERS);
+  return GetEntitySpecifics().managed_user();
+}
+
 const sync_pb::DeviceInfoSpecifics& BaseNode::GetDeviceInfoSpecifics() const {
   DCHECK_EQ(GetModelType(), DEVICE_INFO);
   return GetEntitySpecifics().device_info();