FrameTree::Find only searches relative to local frames.

third_party/WebKit/Source/web/WebLocalFrameImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2013 matching lines @@
 WebLocalFrameImpl* WebLocalFrameImpl::LocalRoot() {
   // This can't use the LocalFrame::localFrameRoot, since it may be called
   // when the WebLocalFrame exists but the core LocalFrame does not.
   // TODO(alexmos, dcheng): Clean this up to only calculate this in one place.
   WebLocalFrameImpl* local_root = this;
   while (local_root->Parent() && local_root->Parent()->IsWebLocalFrame())
     local_root = ToWebLocalFrameImpl(local_root->Parent());
   return local_root;
 }
 
+WebFrame* WebLocalFrameImpl::FindFrameByName(const WebString& name) {
+  Frame* result = GetFrame()->Tree().Find(name);
+  return WebFrame::FromFrame(result);
+}
+
 void WebLocalFrameImpl::SendPings(const WebURL& destination_url) {
   DCHECK(GetFrame());
   DCHECK(context_menu_node_.Get());
   Element* anchor = context_menu_node_->EnclosingLinkEventParentOrSelf();
   if (isHTMLAnchorElement(anchor))
     toHTMLAnchorElement(anchor)->SendPings(destination_url);
 }
 
 bool WebLocalFrameImpl::DispatchBeforeUnloadEvent(bool is_reload) {
   if (!GetFrame())
@@ skipping 553 matching lines @@
 TextCheckerClient& WebLocalFrameImpl::GetTextCheckerClient() const {
   return *text_checker_client_;
 }
 
 void WebLocalFrameImpl::SetTextCheckClient(
     WebTextCheckClient* text_check_client) {
   text_check_client_ = text_check_client;
 }
 
 }  // namespace blink