Cleanup: Remove unnecessary code related to PagePopupDriver.

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 42 matching lines @@
 class GraphicsContext;
 class GraphicsLayer;
 class GraphicsLayerFactory;
 class HitTestResult;
 class HTMLFormControlElement;
 class HTMLInputElement;
 class IntRect;
 class LocalFrame;
 class Node;
 class Page;
-class PagePopupDriver;
 class PopupMenuClient;
 class PopupOpeningObserver;
 class WebCompositorAnimationTimeline;
 
 struct CompositedSelection;
 struct DateTimeChooserParameters;
 struct FrameLoadRequest;
 struct GraphicsDeviceAdapter;
 struct ViewportDescription;
 struct WindowFeatures;
@@ skipping 186 matching lines @@
 private:
     bool canRunModalIfDuringPageDismissal(Frame* mainFrame, DialogType, const String& message);
     void setToolTip(const HitTestResult&);
 
     Cursor m_lastSetMouseCursorForTesting;
 };
 
 } // namespace blink
 
 #endif // ChromeClient_h