[iOS] Refactoring web CRWSessionController user agent code.

ios/web/public/navigation_manager.h

Index: ios/web/public/navigation_manager.h
diff --git a/ios/web/public/navigation_manager.h b/ios/web/public/navigation_manager.h
index f3e106dcba6f44cfdc9a75fd19ffc1dd53c25696..bec6c696e9d91976aa8beacb7be49e8835d33c52 100644
--- a/ios/web/public/navigation_manager.h
+++ b/ios/web/public/navigation_manager.h
@@ -148,6 +148,12 @@ class NavigationManager {
   // reload the page. In nearly all cases pass in true.  If a transient item is
   // showing, initiates a new navigation to its URL.
   virtual void Reload(bool check_for_repost) = 0;
+
+  // Forces the pending item to be loaded using desktop user agent. Note that
+  // the pending item may or may not already exist.
+  // TODO(crbug.com/692303): Remove this when overriding the user agent doesn't
+  // create a new NavigationItem.
+  virtual void OverrideDesktopUserAgentForNextPendingItem() = 0;
 };
 
 }  // namespace web