OOPIF: Fix subframe back/forward after recreating FTNs (try #2).

content/browser/frame_host/frame_tree_node.h

Index: content/browser/frame_host/frame_tree_node.h
diff --git a/content/browser/frame_host/frame_tree_node.h b/content/browser/frame_host/frame_tree_node.h
index d38185808db2c6eb11f4130ed031e24a5b72a7c2..a8a9eedb88c3a255ca36b7418eb74607a396239d 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -98,6 +98,10 @@ class CONTENT_EXPORT FrameTreeNode {
     return replication_state_.name;
   }
 
+  const std::string& unique_name() const {
+    return replication_state_.unique_name;
+  }
+
   size_t child_count() const {
     return children_.size();
   }