Revert of (Set)IsOverridingUserAgent should be called on VisibleItem

ios/chrome/browser/tabs/tab.mm

Index: ios/chrome/browser/tabs/tab.mm
diff --git a/ios/chrome/browser/tabs/tab.mm b/ios/chrome/browser/tabs/tab.mm
index 2071164fd042e4ae786830f8d313b1ea9659dda1..a6eda18221461e7f4268aae932b9dd11ecab1fdc 100644
--- a/ios/chrome/browser/tabs/tab.mm
+++ b/ios/chrome/browser/tabs/tab.mm
@@ -1567,16 +1567,13 @@
   [storeKitLauncher_ openAppStore:appId];
 }
 
-- (BOOL)usesDesktopUserAgent {
-  if (!self.navigationManager)
-    return NO;
-
-  web::NavigationItem* visibleItem = self.navigationManager->GetVisibleItem();
-  return visibleItem && visibleItem->IsOverridingUserAgent();
+- (BOOL)useDesktopUserAgent {
+  web::NavigationItem* currentItem = self.currentNavigationItem;
+  return currentItem && currentItem->IsOverridingUserAgent();
 }
 
 - (void)enableDesktopUserAgent {
-  DCHECK_EQ(self.usesDesktopUserAgent, NO);
+  DCHECK_EQ(self.useDesktopUserAgent, NO);
   DCHECK([self navigationManager]);
   [self navigationManager]->OverrideDesktopUserAgentForNextPendingItem();
 }