Don't cache WebFrame pointers for Autofill, as these can become stale.

chrome/renderer/autofill/form_cache.h

 // Copyright (c) 2011 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 CHROME_RENDERER_AUTOFILL_FORM_CACHE_H_
 #define CHROME_RENDERER_AUTOFILL_FORM_CACHE_H_
 #pragma once
 
 #include <map>
 #include <set>
 #include <vector>
 
 #include "base/string16.h"
 
 namespace webkit_glue {
 struct FormData;
 struct FormDataPredictions;
 }  // namespace webkit_glue
 
 namespace WebKit {
+class WebDocument;
 class WebFormControlElement;
 class WebFrame;
 class WebInputElement;
 class WebSelectElement;
 }  // namespace WebKit
 
 namespace autofill {
 
 // Manages the forms in a RenderView.
 class FormCache {
@@ skipping 14 matching lines @@
   bool ClearFormWithElement(const WebKit::WebInputElement& element);
 
   // For each field in the |form|, sets the field's placeholder text to the
   // field's overall predicted type.  Also sets the title to include the field's
   // heuristic type, server type, and signature; as well as the form's signature
   // and the experiment id for the server predictions.
   bool ShowPredictions(const webkit_glue::FormDataPredictions& form);
 
  private:
   // The cached web frames.
-  std::set<const WebKit::WebFrame*> web_frames_;
+  std::set<WebKit::WebDocument> web_documents_;
 
   // The cached initial values for <select> elements.
   std::map<const WebKit::WebSelectElement, string16> initial_select_values_;
 
   DISALLOW_COPY_AND_ASSIGN(FormCache);
 };
 
 }  // namespace autofill
 
 #endif  // CHROME_RENDERER_AUTOFILL_FORM_CACHE_H_