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 c7c3029150c9625c1acbc6f9ecb6ae0a7926e62c..b814f7866fbcfeb5c7b825102074bc7d9bfbf0db 100644
--- a/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp
@@ -800,19 +800,21 @@ static void paintScrollbar(const Scrollbar* scrollbar, GraphicsContext& context,
     scrollbar->paint(&context, CullRect(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