Let synchronized painting generate correct paint invalidation rects

third_party/WebKit/Source/core/paint/PaintLayer.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index 94ca11eb5669da1ec0491ae13997b17c1625dd2c..9e608e346fb41df3451e3620a5a3a5d829feb1b5 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -2693,11 +2693,15 @@ void PaintLayer::markAncestorChainForNeedsRepaint()
     // Need to access compositingState(). We've ensured correct flag setting when compositingState() changes.
     DisableCompositingQueryAsserts disabler;
 
-    if (compositingState() != NotComposited)
-        return;
-
     PaintLayer* layer = this;
     while (true) {
+        if (layer->compositingState() == PaintsIntoOwnBacking)
+            return;
+        if (CompositedLayerMapping* groupedMapping = layer->groupedMapping()) {
+            groupedMapping->owningLayer().setNeedsRepaint();
+            return;
+        }
+
         PaintLayer* container = layer->parent();
         if (!container) {
             LayoutObject* owner = layer->layoutObject()->frame()->ownerLayoutObject();
@@ -2710,8 +2714,6 @@ void PaintLayer::markAncestorChainForNeedsRepaint()
                 break;
             container->m_needsRepaint = true;
         }
-        if (container->compositingState() != NotComposited)
-            break;
         layer = container;
     }
 }