Repaint on interest rect change

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp

Index: third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
index 3e4f079d35943e1535f6891dce47fb64813f6774..f8a38055ebfe2e2ced5b5c673e7c96f8db1138aa 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -799,19 +799,21 @@ static void paintScrollbar(const Scrollbar* scrollbar, GraphicsContext& context,
     scrollbar->paint(&context, transformedClip);
 }
 
-void PaintLayerCompositor::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& context, GraphicsLayerPaintingPhase, const IntRect& clip) const
+void PaintLayerCompositor::paintContents(const GraphicsLayer* graphicsLayer, GraphicsContext& context, GraphicsLayerPaintingPhase, const IntRect* clip) const
 {
+    IntRect defaultClip;
+    if (RuntimeEnabledFeatures::slimmingPaintSynchronizedPaintingEnabled() && !clip) {
+        defaultClip.setSize(m_layoutView.layoutSize(IncludeScrollbars));
+        clip = &defaultClip;
+    }
+    ASSERT(clip);
+
     if (graphicsLayer == layerForHorizontalScrollbar())
-        paintScrollbar(m_layoutView.frameView()->horizontalScrollbar(), context, clip);
+        paintScrollbar(m_layoutView.frameView()->horizontalScrollbar(), context, *clip);
     else if (graphicsLayer == layerForVerticalScrollbar())
-        paintScrollbar(m_layoutView.frameView()->verticalScrollbar(), context, clip);
+        paintScrollbar(m_layoutView.frameView()->verticalScrollbar(), context, *clip);
     else if (graphicsLayer == layerForScrollCorner())
-        FramePainter(*m_layoutView.frameView()).paintScrollCorner(&context, clip);
-}
-
-void PaintLayerCompositor::paintContentsIfNeeded(const GraphicsLayer* graphicsLayer, GraphicsContext& context, GraphicsLayerPaintingPhase phase) const
-{
-    paintContents(graphicsLayer, context, phase, IntRect());
+        FramePainter(*m_layoutView.frameView()).paintScrollCorner(&context, *clip);
 }
 
 bool PaintLayerCompositor::supportsFixedRootBackgroundCompositing() const