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

ios/web/interstitials/web_interstitial_impl.mm

Index: ios/web/interstitials/web_interstitial_impl.mm
diff --git a/ios/web/interstitials/web_interstitial_impl.mm b/ios/web/interstitials/web_interstitial_impl.mm
index 1a9febb41a5510d446a02e7e28c507fae7d87804..51c49336ecfd7e2b313a590a718758ccfcb3e0f6 100644
--- a/ios/web/interstitials/web_interstitial_impl.mm
+++ b/ios/web/interstitials/web_interstitial_impl.mm
@@ -60,12 +60,9 @@
   GetWebStateImpl()->ShowWebInterstitial(this);
 
   if (new_navigation_) {
-    // TODO(stuartmorgan): Plumb transient entry handling through
-    // NavigationManager, and remove the NavigationManagerImpl and
-    // SessionController usage here.
-    CRWSessionController* sessionController =
-        navigation_manager_->GetSessionController();
-    [sessionController addTransientItemWithURL:url_];
+    // TODO(crbug.com/706578): Plumb transient entry handling through
+    // NavigationManager, and remove the NavigationManagerImpl usage here.
+    navigation_manager_->AddTransientItem(url_);
 
     // Give delegates a chance to set some states on the navigation item.
     GetDelegate()->OverrideItem(navigation_manager_->GetTransientItem());