Add Sync data type for managed users.

sync/internal_api/public/write_node.h

Index: sync/internal_api/public/write_node.h
diff --git a/sync/internal_api/public/write_node.h b/sync/internal_api/public/write_node.h
index 3cb4039a20ad2bd86c3349d2ad78b74eb0355fce..d3781e8b9e10ab10a02f16ae3cc886e15a1f0c05 100644
--- a/sync/internal_api/public/write_node.h
+++ b/sync/internal_api/public/write_node.h
@@ -165,6 +165,10 @@ class SYNC_EXPORT WriteNode : public BaseNode {
   void SetManagedUserSettingSpecifics(
       const sync_pb::ManagedUserSettingSpecifics& specifics);
 
+  // Set the managed user setting specifics (name and value).
+  // Should only be called if GetModelType() == MANAGED_USERS.
+  void SetManagedUserSpecifics(const sync_pb::ManagedUserSpecifics& specifics);
+
   // Set the device info specifics.
   // Should only be called if GetModelType() == DEVICE_INFO.
   void SetDeviceInfoSpecifics(const sync_pb::DeviceInfoSpecifics& specifics);