Remove mainthread overhang painting code

Source/core/page/ChromeClient.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple, Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 137 matching lines @@
     virtual void layoutUpdated(LocalFrame*) const { }
 
     virtual void mouseDidMoveOverElement(const HitTestResult&) = 0;
 
     virtual void setToolTip(const String&, TextDirection) = 0;
 
     virtual void print(LocalFrame*) = 0;
 
     virtual void annotatedRegionsChanged() = 0;
 
-    virtual bool paintCustomOverhangArea(GraphicsContext*, const IntRect&, const IntRect&, const IntRect&) = 0;
-
     virtual PassOwnPtrWillBeRawPtr<ColorChooser> createColorChooser(LocalFrame*, ColorChooserClient*, const Color&) = 0;
 
     // This function is used for:
     //  - Mandatory date/time choosers if !ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     //  - Date/time choosers for types for which LayoutTheme::supportsCalendarPicker
     //    returns true, if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     //  - <datalist> UI for date/time input types regardless of
     //    ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     virtual PassRefPtr<DateTimeChooser> openDateTimeChooser(DateTimeChooserClient*, const DateTimeChooserParameters&) = 0;
 
@@ skipping 69 matching lines @@
 
     virtual void didUpdateTopControls() const { }
 
 protected:
     virtual ~ChromeClient() { }
 };
 
 } // namespace blink
 
 #endif // ChromeClient_h