LayoutTheme: Invalidate cache on WebThemeEngine change.

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

 /*
  * Copyright (C) 2007 Apple Inc.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Collabora Ltd.
  * Copyright (C) 2008, 2009 Google Inc.
  * Copyright (C) 2009 Kenneth Rohde Christiansen
  *
  * 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
@@ skipping 345 matching lines @@
   // The result should not be samller than the scrollbar thickness in order to
   // secure space for scrollbar in popup.
   float deviceScale = 1.0f * scaledSize / originalSize;
   if (style.effectiveZoom() < deviceScale)
     return scaledSize;
   // The value should be zoomed though scrollbars aren't scaled by zoom.
   // crbug.com/432795.
   return originalSize * style.effectiveZoom();
 }
 
+void LayoutThemeDefault::didChangeThemeEngine() {
+  m_menuListArrowWidthInDIP = 0;
+}
+
 // static
 void LayoutThemeDefault::setDefaultFontSize(int fontSize) {
   LayoutThemeFontProvider::setDefaultFontSize(fontSize);
 }
 
 int LayoutThemeDefault::menuListInternalPadding(const ComputedStyle& style,
                                                 int padding) const {
   if (style.appearance() == NoControlPart)
     return 0;
   return padding * style.effectiveZoom();
 }
 
 //
 // Following values are come from default of GTK+
 //
 static const int progressAnimationFrames = 10;
 static const double progressAnimationInterval = 0.125;
 
 double LayoutThemeDefault::animationRepeatIntervalForProgressBar() const {
   return progressAnimationInterval;
 }
 
 double LayoutThemeDefault::animationDurationForProgressBar() const {
   return progressAnimationInterval * progressAnimationFrames *
          2;  // "2" for back and forth
 }
 
 }  // namespace blink