Add a counter and a deprecation message when navigating in an unload handler.

third_party/WebKit/Source/core/loader/FrameLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008 Alp Toker <alp@atoker.com>
  * Copyright (C) Research In Motion Limited 2009. All rights reserved.
  * Copyright (C) 2011 Kris Jordan <krisjordan@gmail.com>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ skipping 240 matching lines @@
     m_currentItem->setVisualViewportScrollPoint(m_frame->host()->visualViewport().visibleRect().location());
 
     if (m_frame->isMainFrame())
         m_currentItem->setPageScaleFactor(m_frame->page()->pageScaleFactor());
 
     client()->didUpdateCurrentHistoryItem();
 }
 
 void FrameLoader::dispatchUnloadEvent()
 {
+    NavigationCounterForUnload counter;
+
     // If the frame is unloading, the provisional loader should no longer be
     // protected. It will be detached soon.
     m_protectProvisionalLoader = false;
     saveScrollState();
 
     if (m_frame->document() && !SVGImage::isInSVGImage(m_frame->document()))
         m_frame->document()->dispatchUnloadEvents();
 
     if (Page* page = m_frame->page())
         page->undoStack().didUnloadFrame(*m_frame);
@@ skipping 1352 matching lines @@
     tracedValue->setString("documentLoaderURL", m_documentLoader ? m_documentLoader->url() : String());
     return tracedValue;
 }
 
 inline void FrameLoader::takeObjectSnapshot() const
 {
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID("loading", "FrameLoader", this, toTracedValue());
 }
 
 } // namespace blink