Add ManagedUserSettings Sync data type.

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 07c896b487c00670882b5f561f1ecaab7949021c..3cb4039a20ad2bd86c3349d2ad78b74eb0355fce 100644
--- a/sync/internal_api/public/write_node.h
+++ b/sync/internal_api/public/write_node.h
@@ -160,6 +160,11 @@ class SYNC_EXPORT WriteNode : public BaseNode {
   // Should only be called if GetModelType() == SESSIONS.
   void SetSessionSpecifics(const sync_pb::SessionSpecifics& specifics);
 
+  // Set the managed user setting specifics (name and value).
+  // Should only be called if GetModelType() == MANAGED_USER_SETTINGS.
+  void SetManagedUserSettingSpecifics(
+      const sync_pb::ManagedUserSettingSpecifics& specifics);
+
   // Set the device info specifics.
   // Should only be called if GetModelType() == DEVICE_INFO.
   void SetDeviceInfoSpecifics(const sync_pb::DeviceInfoSpecifics& specifics);