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

content/browser/frame_host/navigation_entry_impl.cc

Index: content/browser/frame_host/navigation_entry_impl.cc
diff --git a/content/browser/frame_host/navigation_entry_impl.cc b/content/browser/frame_host/navigation_entry_impl.cc
index fc3a57c9a94290261b27f899796b93777015186d..dad94ba030d853b86ddf2e99d377b63661dc054e 100644
--- a/content/browser/frame_host/navigation_entry_impl.cc
+++ b/content/browser/frame_host/navigation_entry_impl.cc
@@ -100,19 +100,11 @@
 }
 
 bool NavigationEntryImpl::TreeNode::MatchesFrame(
-    FrameTreeNode* frame_tree_node) {
+    FrameTreeNode* frame_tree_node) const {
   if (frame_tree_node->frame_tree_node_id() ==
       frame_entry->frame_tree_node_id())
     return true;
 
-  if (frame_tree_node->current_replication_state().unique_name ==
-      frame_entry->frame_unique_name()) {
-    // If we find a match by unique name but not FrameTreeNode ID, then the
-    // FrameTreeNode ID on the entry is stale and should be updated.
-    frame_entry->set_frame_tree_node_id(frame_tree_node->frame_tree_node_id());
-    return true;
-  }
-
   // For now, we set the root FNE's FrameTreeNode ID to -1.
   return frame_tree_node->IsMainFrame() &&
          frame_entry->frame_tree_node_id() == -1;
@@ -121,7 +113,7 @@
 std::unique_ptr<NavigationEntryImpl::TreeNode>
 NavigationEntryImpl::TreeNode::CloneAndReplace(
     FrameTreeNode* frame_tree_node,
-    FrameNavigationEntry* frame_navigation_entry) {
+    FrameNavigationEntry* frame_navigation_entry) const {
   if (frame_tree_node && MatchesFrame(frame_tree_node)) {
     // Replace this node in the cloned tree and prune its children.
     return base::WrapUnique(
@@ -695,6 +687,7 @@
 
 void NavigationEntryImpl::AddOrUpdateFrameEntry(
     FrameTreeNode* frame_tree_node,
+    const std::string& frame_unique_name,
     int64_t item_sequence_number,
     int64_t document_sequence_number,
     SiteInstanceImpl* site_instance,
@@ -714,13 +707,10 @@
 
   // Now check whether we have a TreeNode for the node itself.
   int frame_tree_node_id = frame_tree_node->frame_tree_node_id();
-  const std::string& unique_name =
-      frame_tree_node->current_replication_state().unique_name;
   for (TreeNode* child : parent_node->children) {
-    if (child->frame_entry->frame_tree_node_id() == frame_tree_node_id ||
-        child->frame_entry->frame_unique_name() == unique_name) {
+    if (child->frame_entry->frame_tree_node_id() == frame_tree_node_id) {
       // Update the existing FrameNavigationEntry (e.g., for replaceState).
-      child->frame_entry->UpdateEntry(unique_name, item_sequence_number,
+      child->frame_entry->UpdateEntry(frame_unique_name, item_sequence_number,
                                       document_sequence_number, site_instance,
                                       url, referrer, page_state);
       return;
@@ -731,7 +721,7 @@
   // Unordered list, since we expect to look up entries by frame sequence number
   // or unique name.
   FrameNavigationEntry* frame_entry = new FrameNavigationEntry(
-      frame_tree_node_id, unique_name, item_sequence_number,
+      frame_tree_node_id, frame_unique_name, item_sequence_number,
       document_sequence_number, site_instance, url, referrer);
   frame_entry->set_page_state(page_state);
   parent_node->children.push_back(
@@ -739,9 +729,27 @@
 }
 
 FrameNavigationEntry* NavigationEntryImpl::GetFrameEntry(
-    FrameTreeNode* frame_tree_node) {
+    FrameTreeNode* frame_tree_node) const {
   NavigationEntryImpl::TreeNode* tree_node = FindFrameEntry(frame_tree_node);
   return tree_node ? tree_node->frame_entry.get() : nullptr;
+}
+
+FrameNavigationEntry* NavigationEntryImpl::GetFrameEntryByUniqueName(
+    const std::string& unique_name) const {
+  NavigationEntryImpl::TreeNode* node = nullptr;
+  std::queue<NavigationEntryImpl::TreeNode*> work_queue;
+  work_queue.push(root_node());
+  while (!work_queue.empty()) {
+    node = work_queue.front();
+    work_queue.pop();
+    if (node->frame_entry->frame_unique_name() == unique_name)
+      return node->frame_entry.get();
+
+    // Enqueue any children and keep looking.
+    for (auto& child : node->children)
+      work_queue.push(child);
+  }
+  return nullptr;
 }
 
 void NavigationEntryImpl::SetScreenshotPNGData(
@@ -756,7 +764,7 @@
 }
 
 NavigationEntryImpl::TreeNode* NavigationEntryImpl::FindFrameEntry(
-    FrameTreeNode* frame_tree_node) {
+    FrameTreeNode* frame_tree_node) const {
   NavigationEntryImpl::TreeNode* node = nullptr;
   std::queue<NavigationEntryImpl::TreeNode*> work_queue;
   work_queue.push(root_node());