Revert of OOPIF: Fix subframe back/forward after recreating FTNs.

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index 6afb53557d27cc587d113398d3a48b0f2072e129..546b119998156517090926bdd6a008662d2bfe13 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -435,16 +435,16 @@
   if (!entry)
     return false;
 
-  // TODO(creis): Remove unique_name from the IPC, now that we can rely on the
-  // replication state.
-  DCHECK_EQ(render_frame_host->frame_tree_node()
-                ->current_replication_state()
-                .unique_name,
-            unique_name);
   FrameNavigationEntry* frame_entry =
-      entry->GetFrameEntry(render_frame_host->frame_tree_node());
+      entry->GetFrameEntryByUniqueName(unique_name);
   if (!frame_entry)
     return false;
+
+  // Update the FrameNavigationEntry's FrameTreeNode ID (which is currently the
+  // ID of the old FrameTreeNode that no longer exists) to be the ID of the
+  // newly created frame.
+  frame_entry->set_frame_tree_node_id(
+      render_frame_host->frame_tree_node()->frame_tree_node_id());
 
   return NavigateToEntry(render_frame_host->frame_tree_node(), *frame_entry,
                          *entry, NavigationControllerImpl::NO_RELOAD, false,