Remove platform dependency upon page/Settings class which is a layering violation.

Source/core/platform/ScrollbarTheme.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All Rights Reserved.
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  * modification, are permitted provided that the following conditions
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 #include "config.h"
 #include "core/platform/ScrollbarTheme.h"
 
 #include "RuntimeEnabledFeatures.h"
-#include "core/page/Settings.h"
 #include "core/platform/ScrollbarThemeClient.h"
 #include "core/platform/graphics/GraphicsContext.h"
 #include "core/platform/mock/ScrollbarThemeMock.h"
 #include "core/platform/mock/ScrollbarThemeOverlayMock.h"
 
 namespace WebCore {
 
 ScrollbarTheme* ScrollbarTheme::theme()
 {
-    if (Settings::mockScrollbarsEnabled()) {
+    if (ScrollbarTheme::mockScrollbarsEnabled()) {
         if (RuntimeEnabledFeatures::overlayScrollbarsEnabled()) {
             DEFINE_STATIC_LOCAL(ScrollbarThemeOverlayMock, overlayMockTheme, ());
             return &overlayMockTheme;
         }
 
         DEFINE_STATIC_LOCAL(ScrollbarThemeMock, mockTheme, ());
         return &mockTheme;
     }
     return nativeTheme();
 }
 
+bool ScrollbarTheme::gMockScrollbarsEnabled = false;
+
+void ScrollbarTheme::setMockScrollbarsEnabled(bool flag)
+{
+    gMockScrollbarsEnabled = flag;
+}
+
+bool ScrollbarTheme::mockScrollbarsEnabled()
+{
+    return gMockScrollbarsEnabled;
+}
+
 bool ScrollbarTheme::paint(ScrollbarThemeClient* scrollbar, GraphicsContext* graphicsContext, const IntRect& damageRect)
 {
     // Create the ScrollbarControlPartMask based on the damageRect
     ScrollbarControlPartMask scrollMask = NoPart;
 
     IntRect backButtonStartPaintRect;
     IntRect backButtonEndPaintRect;
     IntRect forwardButtonStartPaintRect;
     IntRect forwardButtonEndPaintRect;
     if (hasButtons(scrollbar)) {
@@ skipping 246 matching lines @@
 void ScrollbarTheme::paintOverhangBackground(ScrollView*, GraphicsContext* context, const IntRect& horizontalOverhangRect, const IntRect& verticalOverhangRect, const IntRect& dirtyRect)
 {
     context->setFillColor(Color::white);
     if (!horizontalOverhangRect.isEmpty())
         context->fillRect(intersection(horizontalOverhangRect, dirtyRect));
     if (!verticalOverhangRect.isEmpty())
         context->fillRect(intersection(verticalOverhangRect, dirtyRect));
 }
 
 }