LayoutTheme: Invalidate cache on WebThemeEngine change.

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

 /*
  * This file is part of the theme implementation for form controls in WebCore.
  *
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Computer, Inc.
  *
  * 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 40 matching lines @@
  protected:
   explicit LayoutTheme(Theme*);
 
  public:
   virtual ~LayoutTheme() {}
 
   static LayoutTheme& theme();
 
   virtual ThemePainter& painter() = 0;
 
+  // This function is called after associated WebThemeEngine instance
+  // was replaced. This is called only in tests.
+  virtual void didChangeThemeEngine() {}
+
   static void setSizeIfAuto(ComputedStyle&, const IntSize&);
 
   // This method is called whenever style has been computed for an element and
   // the appearance property has been set to a value other than "none".
   // The theme should map in all of the appropriate metrics and defaults given
   // the contents of the style. This includes sophisticated operations like
   // selection of control size based off the font, the disabling of appearance
   // when certain other properties like "border" are set, or if the appearance
   // is not supported by the theme.
   void adjustStyle(ComputedStyle&, Element*);
@@ skipping 215 matching lines @@
   static const RGBA32 defaultTapHighlightColor = 0x66000000;
 
   static const RGBA32 defaultCompositionBackgroundColor = 0xFFFFDD55;
 
   Theme* m_platformTheme;  // The platform-specific theme.
 };
 
 }  // namespace blink
 
 #endif  // LayoutTheme_h