Update comments about scrollbar thickness.

third_party/WebKit/Source/core/paint/ThemePainterDefault.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 272 matching lines @@
     const LayoutBox& box,
     const IntRect& rect,
     WebThemeEngine::ExtraParams& extraParams) {
   const int left = rect.x() + box.borderLeft();
   const int right = rect.x() + rect.width() - box.borderRight();
   const int middle = rect.y() + rect.height() / 2;
 
   extraParams.menuList.arrowY = middle;
   float arrowBoxWidth = m_theme.clampedMenuListArrowPaddingSize(
       box.frameView()->getHostWindow(), box.styleRef());
-  float arrowScaleFactor = arrowBoxWidth / m_theme.scrollbarThicknessInDIP();
+  float arrowScaleFactor = arrowBoxWidth / m_theme.menuListArrowWidthInDIP();
   if (useMockTheme()) {
     // The size and position of the drop-down button is different between
     // the mock theme and the regular aura theme.
 
     // Padding inside the arrowBox.
     float extraPadding = 2 * arrowScaleFactor;
     float arrowSize =
         std::min(arrowBoxWidth,
                  static_cast<float>(rect.height() - box.borderTop() -
                                     box.borderBottom())) -
@@ skipping 161 matching lines @@
   DEFINE_STATIC_REF(Image, cancelPressedImage,
                     (Image::loadPlatformResource("searchCancelPressed")));
   paintInfo.context.drawImage(LayoutTheme::isPressed(cancelButtonObject)
                                   ? cancelPressedImage
                                   : cancelImage,
                               paintingRect);
   return false;
 }
 
 }  // namespace blink