NS_IMETHODIMP
WebBrowserPersistResourcesChild::VisitDocument(nsIWebBrowserPersistDocument* aDocument,
                                               nsIWebBrowserPersistDocument* aSubDocument)
{
    auto* subActor = new WebBrowserPersistDocumentChild();
    dom::PBrowserChild* grandManager = Manager()->Manager();
    // As a consequence of how PWebBrowserPersistDocumentConstructor can be
    // sent by both the parent and the child, we must pass the outerWindowID
    // argument here. We pass 0, though note that this argument is actually
    // just ignored when passed up to the parent from the child.
    if (!grandManager->SendPWebBrowserPersistDocumentConstructor(subActor, 0)) {
        // NOTE: subActor is freed at this point.
        return NS_ERROR_FAILURE;
    }
    // ...but here, IPC won't free subActor until after this returns
    // to the event loop.

    // The order of these two messages will be preserved, because
    // they're the same toplevel protocol and priority.
    //
    // With this ordering, it's always the transition out of START
    // state that causes a document's parent actor to be exposed to
    // XPCOM (for both parent->child and child->parent construction),
    // which simplifies the lifetime management.
    SendVisitDocument(subActor);
    subActor->Start(aSubDocument);
    return NS_OK;
}
NS_IMETHODIMP
WebBrowserPersistResourcesChild::VisitDocument(
    nsIWebBrowserPersistDocument* aDocument,
    nsIWebBrowserPersistDocument* aSubDocument) {
  auto* subActor = new WebBrowserPersistDocumentChild();
  // As a consequence of how PWebBrowserPersistDocumentConstructor
  // can be sent by both the parent and the child, we must pass the
  // aBrowser and outerWindowID arguments here, but the values are
  // ignored by the parent.  In particular, the TabChild in which
  // persistence started does not necessarily exist at this point;
  // see bug 1203602.
  if (!Manager()->Manager()->SendPWebBrowserPersistDocumentConstructor(
          subActor, nullptr, 0)) {
    // NOTE: subActor is freed at this point.
    return NS_ERROR_FAILURE;
  }
  // ...but here, IPC won't free subActor until after this returns
  // to the event loop.

  // The order of these two messages will be preserved, because
  // they're the same toplevel protocol and priority.
  //
  // With this ordering, it's always the transition out of START
  // state that causes a document's parent actor to be exposed to
  // XPCOM (for both parent->child and child->parent construction),
  // which simplifies the lifetime management.
  SendVisitDocument(subActor);
  subActor->Start(aSubDocument);
  return NS_OK;
}