Blink Support for Overlay Scrollbar Animation

Source/platform/scroll/ScrollbarThemeAura.cpp

 /*
  * Copyright (c) 2008, 2009, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 23 matching lines @@
 #include "platform/LayoutTestSupport.h"
 #include "platform/PlatformMouseEvent.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/scroll/ScrollbarThemeClient.h"
 #include "platform/scroll/ScrollbarThemeOverlay.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebRect.h"
 #include "public/platform/WebThemeEngine.h"
 
+namespace {
+
+const int kDefaultOverlayScrollbarThumbThickness = 13;
+
+} // namespace
+
 namespace blink {
 
 static bool useMockTheme()
 {
     return LayoutTestSupport::isRunningLayoutTest();
 }
 
 ScrollbarTheme* ScrollbarTheme::nativeTheme()
 {
     if (RuntimeEnabledFeatures::overlayScrollbarsEnabled()) {
-        DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (10, 0, ScrollbarThemeOverlay::AllowHitTest));
+        DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (kDefaultOverlayScrollbarThumbThickness, 0, ScrollbarThemeOverlay::AllowHitTest));
         return &theme;
     }
 
     DEFINE_STATIC_LOCAL(ScrollbarThemeAura, theme, ());
     return &theme;
 }
 
 int ScrollbarThemeAura::scrollbarThickness(ScrollbarControlSize controlSize)
 {
     // Horiz and Vert scrollbars are the same thickness.
@@ skipping 95 matching lines @@
     if (scrollbar->orientation() == VerticalScrollbar) {
         IntSize size = blink::Platform::current()->themeEngine()->getSize(blink::WebThemeEngine::PartScrollbarVerticalThumb);
         return size.height();
     }
 
     IntSize size = blink::Platform::current()->themeEngine()->getSize(blink::WebThemeEngine::PartScrollbarHorizontalThumb);
     return size.width();
 }
 
 } // namespace blink