Remove mainthread overhang painting code

Source/platform/scroll/ScrollbarThemeMacCommon.mm

Index: Source/platform/scroll/ScrollbarThemeMacCommon.mm
diff --git a/Source/platform/scroll/ScrollbarThemeMacCommon.mm b/Source/platform/scroll/ScrollbarThemeMacCommon.mm
index ca4a59859db8831d1ef3678ea735bcddff0a6e25..efca048f10662bc8a919c6da6e984e2210036814 100644
--- a/Source/platform/scroll/ScrollbarThemeMacCommon.mm
+++ b/Source/platform/scroll/ScrollbarThemeMacCommon.mm
@@ -130,140 +130,6 @@ void ScrollbarThemeMacCommon::paintGivenTickmarks(GraphicsContext* context, Scro
     }
 }
 
-void ScrollbarThemeMacCommon::paintOverhangBackground(GraphicsContext* context, const IntRect& horizontalOverhangRect, const IntRect& verticalOverhangRect, const IntRect& dirtyRect)
-{
-    const bool hasHorizontalOverhang = !horizontalOverhangRect.isEmpty();
-    const bool hasVerticalOverhang = !verticalOverhangRect.isEmpty();
-
-    GraphicsContextStateSaver stateSaver(*context);
-
-    if (!m_overhangPattern) {
-        // Lazily load the linen pattern image used for overhang drawing.
-        RefPtr<Image> patternImage = Image::loadPlatformResource("overhangPattern");
-        m_overhangPattern = Pattern::createBitmapPattern(patternImage);
-    }
-    context->setFillPattern(m_overhangPattern);
-    if (hasHorizontalOverhang)
-        context->fillRect(intersection(horizontalOverhangRect, dirtyRect));
-    if (hasVerticalOverhang)
-        context->fillRect(intersection(verticalOverhangRect, dirtyRect));
-}
-
-void ScrollbarThemeMacCommon::paintOverhangShadows(GraphicsContext* context, const IntSize& scrollOffset, const IntRect& horizontalOverhangRect, const IntRect& verticalOverhangRect, const IntRect& dirtyRect)
-{
-    // The extent of each shadow in pixels.
-    const int kShadowSize = 4;
-    // Offset of negative one pixel to make the gradient blend with the toolbar's bottom border.
-    const int kToolbarShadowOffset = -1;
-    const struct {
-        float stop;
-        Color color;
-    } kShadowColors[] = {
-        { 0.000, Color(0, 0, 0, 255) },
-        { 0.125, Color(0, 0, 0, 57) },
-        { 0.375, Color(0, 0, 0, 41) },
-        { 0.625, Color(0, 0, 0, 18) },
-        { 0.875, Color(0, 0, 0, 6) },
-        { 1.000, Color(0, 0, 0, 0) }
-    };
-    const unsigned kNumShadowColors = sizeof(kShadowColors)/sizeof(kShadowColors[0]);
-
-    const bool hasHorizontalOverhang = !horizontalOverhangRect.isEmpty();
-    const bool hasVerticalOverhang = !verticalOverhangRect.isEmpty();
-    // Prefer non-additive shadows, but degrade to additive shadows if there is vertical overhang.
-    const bool useAdditiveShadows = hasVerticalOverhang;
-
-    GraphicsContextStateSaver stateSaver(*context);
-
-    FloatPoint shadowCornerOrigin;
-    FloatPoint shadowCornerOffset;
-
-    // Draw the shadow for the horizontal overhang.
-    if (hasHorizontalOverhang) {
-        int toolbarShadowHeight = kShadowSize;
-        RefPtr<Gradient> gradient;
-        IntRect shadowRect = horizontalOverhangRect;
-        shadowRect.setHeight(kShadowSize);
-        if (scrollOffset.height() < 0) {
-            if (useAdditiveShadows) {
-                toolbarShadowHeight = std::min(horizontalOverhangRect.height(), kShadowSize);
-            } else if (horizontalOverhangRect.height() < 2 * kShadowSize + kToolbarShadowOffset) {
-                // Split the overhang area between the web content shadow and toolbar shadow if it's too small.
-                shadowRect.setHeight((horizontalOverhangRect.height() + 1) / 2);
-                toolbarShadowHeight = horizontalOverhangRect.height() - shadowRect.height() - kToolbarShadowOffset;
-            }
-            shadowRect.setY(horizontalOverhangRect.maxY() - shadowRect.height());
-            gradient = Gradient::create(FloatPoint(0, shadowRect.maxY()), FloatPoint(0, shadowRect.maxY() - kShadowSize));
-            shadowCornerOrigin.setY(shadowRect.maxY());
-            shadowCornerOffset.setY(-kShadowSize);
-        } else {
-            gradient = Gradient::create(FloatPoint(0, shadowRect.y()), FloatPoint(0, shadowRect.maxY()));
-            shadowCornerOrigin.setY(shadowRect.y());
-        }
-        if (hasVerticalOverhang) {
-            shadowRect.setWidth(shadowRect.width() - verticalOverhangRect.width());
-            if (scrollOffset.width() < 0) {
-                shadowRect.setX(shadowRect.x() + verticalOverhangRect.width());
-                shadowCornerOrigin.setX(shadowRect.x());
-                shadowCornerOffset.setX(-kShadowSize);
-            } else {
-                shadowCornerOrigin.setX(shadowRect.maxX());
-            }
-        }
-        for (unsigned i = 0; i < kNumShadowColors; i++)
-            gradient->addColorStop(kShadowColors[i].stop, kShadowColors[i].color);
-        context->setFillGradient(gradient);
-        context->fillRect(intersection(shadowRect, dirtyRect));
-
-        // Draw a drop-shadow from the toolbar.
-        if (scrollOffset.height() < 0) {
-            shadowRect.setY(kToolbarShadowOffset);
-            shadowRect.setHeight(toolbarShadowHeight);
-            gradient = Gradient::create(FloatPoint(0, shadowRect.y()), FloatPoint(0, shadowRect.y() + kShadowSize));
-            for (unsigned i = 0; i < kNumShadowColors; i++)
-                gradient->addColorStop(kShadowColors[i].stop, kShadowColors[i].color);
-            context->setFillGradient(gradient);
-            context->fillRect(intersection(shadowRect, dirtyRect));
-        }
-    }
-
-    // Draw the shadow for the vertical overhang.
-    if (hasVerticalOverhang) {
-        RefPtr<Gradient> gradient;
-        IntRect shadowRect = verticalOverhangRect;
-        shadowRect.setWidth(kShadowSize);
-        if (scrollOffset.width() < 0) {
-            shadowRect.setX(verticalOverhangRect.maxX() - shadowRect.width());
-            gradient = Gradient::create(FloatPoint(shadowRect.maxX(), 0), FloatPoint(shadowRect.x(), 0));
-        } else {
-            gradient = Gradient::create(FloatPoint(shadowRect.x(), 0), FloatPoint(shadowRect.maxX(), 0));
-        }
-        for (unsigned i = 0; i < kNumShadowColors; i++)
-            gradient->addColorStop(kShadowColors[i].stop, kShadowColors[i].color);
-        context->setFillGradient(gradient);
-        context->fillRect(intersection(shadowRect, dirtyRect));
-
-        // Draw a drop-shadow from the toolbar.
-        shadowRect = verticalOverhangRect;
-        shadowRect.setY(kToolbarShadowOffset);
-        shadowRect.setHeight(kShadowSize);
-        gradient = Gradient::create(FloatPoint(0, shadowRect.y()), FloatPoint(0, shadowRect.maxY()));
-        for (unsigned i = 0; i < kNumShadowColors; i++)
-            gradient->addColorStop(kShadowColors[i].stop, kShadowColors[i].color);
-        context->setFillGradient(gradient);
-        context->fillRect(intersection(shadowRect, dirtyRect));
-    }
-
-    // If both rectangles present, draw a radial gradient for the corner.
-    if (hasHorizontalOverhang && hasVerticalOverhang) {
-        RefPtr<Gradient> gradient = Gradient::create(shadowCornerOrigin, 0, shadowCornerOrigin, kShadowSize);
-        for (unsigned i = 0; i < kNumShadowColors; i++)
-            gradient->addColorStop(kShadowColors[i].stop, kShadowColors[i].color);
-        context->setFillGradient(gradient);
-        context->fillRect(FloatRect(shadowCornerOrigin.x() + shadowCornerOffset.x(), shadowCornerOrigin.y() + shadowCornerOffset.y(), kShadowSize, kShadowSize));
-    }
-}
-
 void ScrollbarThemeMacCommon::paintTickmarks(GraphicsContext* context, ScrollbarThemeClient* scrollbar, const IntRect& rect)
 {
     // Note: This is only used for css-styled scrollbars on mac.