LayoutTheme: Invalidate cache on WebThemeEngine change.

third_party/WebKit/Source/core/layout/LayoutThemeDefault.h

 /*
  * This file is part of the WebKit project.
  *
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) 2006 Michael Emmel mike.emmel@gmail.com
  * Copyright (C) 2007 Holger Hans Peter Freyther
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008, 2009 Google, Inc.
  * All rights reserved.
  * Copyright (C) 2009 Kenneth Rohde Christiansen
@@ skipping 129 matching lines @@
   ~LayoutThemeDefault() override;
   bool shouldUseFallbackTheme(const ComputedStyle&) const override;
 
   IntRect determinateProgressValueRectFor(LayoutProgress*,
                                           const IntRect&) const;
   IntRect indeterminateProgressValueRectFor(LayoutProgress*,
                                             const IntRect&) const;
 
  private:
   ThemePainter& painter() override { return m_painter; }
+  void didChangeThemeEngine() override;
 
   int menuListInternalPadding(const ComputedStyle&, int padding) const;
 
   static const RGBA32 defaultTapHighlightColor = 0x2e000000;  // 18% black.
   static double m_caretBlinkInterval;
 
   static unsigned m_activeSelectionBackgroundColor;
   static unsigned m_activeSelectionForegroundColor;
   static unsigned m_inactiveSelectionBackgroundColor;
   static unsigned m_inactiveSelectionForegroundColor;
 
   ThemePainterDefault m_painter;
   int m_menuListArrowWidthInDIP = 0;
 };
 
 }  // namespace blink
 
 #endif  // LayoutThemeDefault_h