FrameTree::Find only searches relative to local frames.

third_party/WebKit/Source/web/WebViewImpl.h

 /*
  * Copyright (C) 2010 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 154 matching lines @@
   void SetTabKeyCyclesThroughElements(bool value) override;
   bool IsActive() const override;
   void SetIsActive(bool value) override;
   void SetDomainRelaxationForbidden(bool, const WebString& scheme) override;
   void SetWindowFeatures(const WebWindowFeatures&) override;
   void SetOpenedByDOM() override;
   void ResizeWithBrowserControls(const WebSize&,
                                  float browser_controls_height,
                                  bool browser_controls_shrink_layout) override;
   WebFrame* MainFrame() override;
-  WebFrame* FindFrameByName(const WebString& name,
-                            WebFrame* relative_to_frame) override;
   WebLocalFrame* FocusedFrame() override;
   void SetFocusedFrame(WebFrame*) override;
   void FocusDocumentView(WebFrame*) override;
   void SetInitialFocus(bool reverse) override;
   void ClearFocusedElement() override;
   bool ScrollFocusedEditableElementIntoRect(const WebRect&) override;
   void SmoothScroll(int target_x, int target_y, long duration_ms) override;
   void ZoomToFindInPageRect(const WebRect&) override;
   void AdvanceFocus(bool reverse) override;
   void AdvanceFocusAcrossFrames(WebFocusType,
@@ skipping 556 matching lines @@
   Persistent<ResizeViewportAnchor> resize_viewport_anchor_;
 };
 
 // We have no ways to check if the specified WebView is an instance of
 // WebViewImpl because WebViewImpl is the only implementation of WebView.
 DEFINE_TYPE_CASTS(WebViewImpl, WebView, webView, true, true);
 
 }  // namespace blink
 
 #endif