Set track_start on solid color layers to the margin.

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 229 matching lines @@
 {
     ScrollbarTheme* theme = scrollbar->theme();
     blink::WebScrollbarThemePainter painter(theme, scrollbar);
     OwnPtr<blink::WebScrollbarThemeGeometry> geometry(blink::WebScrollbarThemeGeometryNative::create(theme));
 
     OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createScrollbarLayer(new blink::WebScrollbarImpl(scrollbar), painter, geometry.leakPtr()));
     GraphicsLayer::registerContentsLayer(scrollbarLayer->layer());
     return scrollbarLayer.release();
 }
 
-PassOwnPtr<WebScrollbarLayer> ScrollingCoordinator::createSolidColorScrollbarLayer(ScrollbarOrientation orientation, int thumbThickness, bool isLeftSideVerticalScrollbar)
+PassOwnPtr<WebScrollbarLayer> ScrollingCoordinator::createSolidColorScrollbarLayer(ScrollbarOrientation orientation, int thumbThickness, int trackStart, bool isLeftSideVerticalScrollbar)
 {
     blink::WebScrollbar::Orientation webOrientation = (orientation == HorizontalScrollbar) ? blink::WebScrollbar::Horizontal : blink::WebScrollbar::Vertical;
-    OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createSolidColorScrollbarLayer(webOrientation, thumbThickness, isLeftSideVerticalScrollbar));
+    OwnPtr<WebScrollbarLayer> scrollbarLayer = adoptPtr(blink::Platform::current()->compositorSupport()->createSolidColorScrollbarLayer(webOrientation, thumbThickness, trackStart, isLeftSideVerticalScrollbar));
     GraphicsLayer::registerContentsLayer(scrollbarLayer->layer());
     return scrollbarLayer.release();
 }
 
 static void detachScrollbarLayer(GraphicsLayer* scrollbarGraphicsLayer)
 {
     ASSERT(scrollbarGraphicsLayer);
 
     scrollbarGraphicsLayer->setContentsToPlatformLayer(0);
     scrollbarGraphicsLayer->setDrawsContent(true);
@@ skipping 57 matching lines @@
             return;
         }
 
         WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, orientation);
         if (!scrollbarLayer) {
             Settings* settings = m_page->mainFrame()->document()->settings();
 
             OwnPtr<WebScrollbarLayer> webScrollbarLayer;
             if (settings->useSolidColorScrollbars()) {
                 ASSERT(RuntimeEnabledFeatures::overlayScrollbarsEnabled());
-                webScrollbarLayer = createSolidColorScrollbarLayer(orientation, scrollbar->theme()->thumbThickness(scrollbar), scrollableArea->shouldPlaceVerticalScrollbarOnLeft());
+                webScrollbarLayer = createSolidColorScrollbarLayer(orientation, scrollbar->theme()->thumbThickness(scrollbar), scrollbar->theme()->trackPosition(scrollbar), scrollableArea->shouldPlaceVerticalScrollbarOnLeft());
             } else {
                 webScrollbarLayer = createScrollbarLayer(scrollbar);
             }
             scrollbarLayer = addWebScrollbarLayer(scrollableArea, orientation, webScrollbarLayer.release());
         }
 
         // Root layer non-overlay scrollbars should be marked opaque to disable
         // blending.
         bool isOpaqueScrollbar = !scrollbar->isOverlayScrollbar();
         if (!scrollbarGraphicsLayer->contentsOpaque())
@@ skipping 614 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? toWebLayer(frameView->layerForScrolling()) : 0)
         return blink::WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace WebCore