Set user agent type of transient item the same as pending item.

ios/web/navigation/navigation_manager_impl.mm

Index: ios/web/navigation/navigation_manager_impl.mm
diff --git a/ios/web/navigation/navigation_manager_impl.mm b/ios/web/navigation/navigation_manager_impl.mm
index b1cb00ee08f28b94e62bc900685036b21e46650e..2e6b6ab336926d0c0bf02e527d4a2acb5bdae9c6 100644
--- a/ios/web/navigation/navigation_manager_impl.mm
+++ b/ios/web/navigation/navigation_manager_impl.mm
@@ -170,6 +170,16 @@ bool AreURLsInPageNavigation(const GURL& existing_url, const GURL& new_url) {
   delegate_->GetWebState()->OpenURL(params);
 }
 
+void NavigationManagerImpl::AddTransientItem(const GURL& url) {
+  [session_controller_ addTransientItemWithURL:url];
+  DCHECK(GetTransientItem());
+
+  // Transient item can only be added for pending non-app-specific loads.
+  DCHECK(GetPendingItem());
+  DCHECK_NE(UserAgentType::NONE, GetPendingItem()->GetUserAgentType());
+  GetTransientItem()->SetUserAgentType(GetPendingItem()->GetUserAgentType());
+}
+
 void NavigationManagerImpl::AddPendingItem(
     const GURL& url,
     const web::Referrer& referrer,