(Set)IsOverridingUserAgent should be called on VisibleItem

ios/web/navigation/crw_session_controller.mm

Index: ios/web/navigation/crw_session_controller.mm
diff --git a/ios/web/navigation/crw_session_controller.mm b/ios/web/navigation/crw_session_controller.mm
index d03bf9481386425669ff7c8f9bbaf4f29a8a8796..90525e5eb90ce36f73a49ac321de4612d529ccef 100644
--- a/ios/web/navigation/crw_session_controller.mm
+++ b/ios/web/navigation/crw_session_controller.mm
@@ -74,10 +74,6 @@ @interface CRWSessionController () {
   // interval since 1970.
   NSTimeInterval _lastVisitedTimestamp;
 
-  // If |YES|, override |currentEntry.useDesktopUserAgent| and create the
-  // pending entry using the desktop user agent.
-  BOOL _useDesktopUserAgentForNextPendingItem;
-
   // The browser state associated with this CRWSessionController;
   web::BrowserState* _browserState;  // weak
 
@@ -496,10 +492,10 @@ - (void)pushNewItemWithURL:(const GURL&)URL
                 transition:(ui::PageTransition)transition {
   DCHECK(![self pendingEntry]);
   DCHECK([self currentEntry]);
-  web::NavigationItem* currentItem = [self currentEntry].navigationItem;
+  web::NavigationItem* visibleItem = [self visibleEntry].navigationItem;
   CHECK(web::history_state_util::IsHistoryStateChangeValid(
-      currentItem->GetURL(), URL));
-  web::Referrer referrer(currentItem->GetURL(), web::ReferrerPolicyDefault);
+      visibleItem->GetURL(), URL));
+  web::Referrer referrer(visibleItem->GetURL(), web::ReferrerPolicyDefault);
 
   base::scoped_nsobject<CRWSessionEntry> pushedEntry([self
       sessionEntryWithURL:URL
@@ -508,7 +504,7 @@ - (void)pushNewItemWithURL:(const GURL&)URL
            initiationType:web::NavigationInitiationType::USER_INITIATED]);
 
   web::NavigationItemImpl* pushedItem = [pushedEntry navigationItemImpl];
-  pushedItem->SetIsOverridingUserAgent(currentItem->IsOverridingUserAgent());
+  pushedItem->SetIsOverridingUserAgent(visibleItem->IsOverridingUserAgent());
   pushedItem->SetSerializedStateObject(stateObject);
   pushedItem->SetIsCreatedFromPushState(true);
   web::SSLStatus& sslStatus = [self currentEntry].navigationItem->GetSSL();