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 da2ae03a14d715f438312e472af75142eecc141b..d4d0857b74a54a31e56f18b4a34138c989c9abe8 100644
--- a/ios/web/navigation/navigation_manager_impl.mm
+++ b/ios/web/navigation/navigation_manager_impl.mm
@@ -170,6 +170,15 @@ bool AreURLsInPageNavigation(const GURL& existing_url, const GURL& new_url) {
   delegate_->GetWebState()->OpenURL(params);
 }
 
+void NavigationManagerImpl::AddTransientItem(const GURL& url) {
+  [session_controller_ addTransientItemWithURL:url];
+
+  // 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,