Remove existing FrameNavigationEntry when new named frame is added.

content/browser/frame_host/navigation_entry_impl.h

Index: content/browser/frame_host/navigation_entry_impl.h
diff --git a/content/browser/frame_host/navigation_entry_impl.h b/content/browser/frame_host/navigation_entry_impl.h
index 35603af62ed8e4891ecf8176d6e9ccb43e5f7f99..1cc0b01117ffd4c680aae0a75ea3a2cf720ca83f 100644
--- a/content/browser/frame_host/navigation_entry_impl.h
+++ b/content/browser/frame_host/navigation_entry_impl.h
@@ -233,6 +233,10 @@ class CONTENT_EXPORT NavigationEntryImpl
   // during session history navigations, when the child items no longer apply.
   void ClearChildren(FrameTreeNode* frame_tree_node);
 
+  // Removes the subframe FrameNavigationEntry matching the unique name of
+  // the |frame_tree_node|, if any, and all of its children.
+  void ClearMatchingFrameEntries(FrameTreeNode* frame_tree_node);
+
   void set_unique_id(int unique_id) {
     unique_id_ = unique_id;
   }