Keep track in the browser of which frames have onunload and onbeforeunload handlers.

content/browser/frame_host/navigation_request.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 CONTENT_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
 #include "content/browser/loader/navigation_url_loader_delegate.h"
 #include "content/common/content_export.h"
 #include "content/common/frame_message_enums.h"
 #include "content/common/navigation_params.h"
 #include "content/public/browser/navigation_throttle.h"
 #include "content/public/common/previews_state.h"
 
 namespace content {
 
@@ skipping 225 matching lines @@
 
   std::unique_ptr<NavigationHandleImpl> navigation_handle_;
 
   // Holds the ResourceResponse and the StreamHandle for the navigation while
   // the WillProcessResponse checks are performed by the NavigationHandle.
   scoped_refptr<ResourceResponse> response_;
   std::unique_ptr<StreamHandle> body_;
 
   base::Closure on_start_checks_complete_closure_;
 
+  base::WeakPtrFactory<NavigationRequest> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(NavigationRequest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_REQUEST_H_