FrameTree::Find only searches relative to local frames.

third_party/WebKit/public/web/WebLocalFrame.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebLocalFrame_h
 #define WebLocalFrame_h
 
 #include <set>
 #include "WebCompositionUnderline.h"
 #include "WebFrame.h"
@@ skipping 92 matching lines @@
   virtual void SetAutofillClient(WebAutofillClient*) = 0;
   virtual WebAutofillClient* AutofillClient() = 0;
   virtual void SetDevToolsAgentClient(WebDevToolsAgentClient*) = 0;
   virtual WebDevToolsAgent* DevToolsAgent() = 0;
 
   // Hierarchy ----------------------------------------------------------
 
   // Get the highest-level LocalFrame in this frame's in-process subtree.
   virtual WebLocalFrame* LocalRoot() = 0;
 
+  // Returns the frame identified by the given name.  This method supports
+  // pseudo-names like _self, _top, and _blank.  It traverses the entire
+  // browsing instance containing this frame, looking for a frame that matches
+  // the given name (but note some caveats around browsing instance boundaries
+  // tracked in https://crbug.com/718489).
+  virtual WebFrame* FindFrameByName(const WebString& name) = 0;
+
   // Navigation Ping --------------------------------------------------------
 
   virtual void SendPings(const WebURL& destination_url) = 0;
 
   // Navigation ----------------------------------------------------------
 
   // Runs beforeunload handlers for this frame and returns the value returned
   // by handlers.
   // Note: this may lead to the destruction of the frame.
   virtual bool DispatchBeforeUnloadEvent(bool is_reload) = 0;
@@ skipping 442 matching lines @@
   // to call these on a WebLocalFrame.
   bool IsWebLocalFrame() const override = 0;
   WebLocalFrame* ToWebLocalFrame() override = 0;
   bool IsWebRemoteFrame() const override = 0;
   WebRemoteFrame* ToWebRemoteFrame() override = 0;
 };
 
 }  // namespace blink
 
 #endif  // WebLocalFrame_h