(WIP) Invalidation during painting (for synchronized painting)

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

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index 247131c992ee286e3388696ab902b38545ceef4c..eaf87991edca2a39b254205b80f6c2e64d05753c 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -525,6 +525,8 @@ PaintLayerPainter::PaintResult PaintLayerPainter::paintFragmentByApplyingTransfo
     // Now do a paint with the root layer shifted to be us.
     PaintLayerPaintingInfo transformedPaintingInfo(&m_paintLayer, LayoutRect(enclosingIntRect(transform.inverse().mapRect(paintingInfo.paintDirtyRect))), paintingInfo.globalPaintFlags(),
         adjustedSubPixelAccumulation);
+    if (paintingInfo.ancestorHasNonIdentityAndNonTranslateTransform || !transform.isIdentityOrTranslation())
+        transformedPaintingInfo.ancestorHasNonIdentityAndNonTranslateTransform = true;
     transformedPaintingInfo.ancestorHasClipPathClipping = paintingInfo.ancestorHasClipPathClipping;
     return paintLayerContentsAndReflection(context, transformedPaintingInfo, paintFlags, ForceSingleFragment);
 }
@@ -664,6 +666,16 @@ void PaintLayerPainter::paintFragmentWithPhase(PaintPhase phase, const PaintLaye
     }
     PaintInfo paintInfo(context, pixelSnappedIntRect(newCullRect), phase,
         paintingInfo.globalPaintFlags(), paintFlags, paintingInfo.rootLayer->layoutObject());
+    Optional<PaintInvalidationState> paintInvalidationState;
+    if (RuntimeEnabledFeatures::slimmingPaintSynchronizedPaintingEnabled()) {
+        unsigned flags = 0;
+        if (clipState == HasClipped || paintingInfo.clipToDirtyRect)
+            flags |= PaintInvalidationState::HasClip;
+        if (paintingInfo.ancestorHasNonIdentityAndNonTranslateTransform)
+            flags |= PaintInvalidationState::HasNonIdentityAndNonTranslateTransform;
+        paintInvalidationState.emplace(*paintingInfo.rootLayer->layoutObject(), clipRect.rect(), flags);
+        paintInfo.paintInvalidationState = &*paintInvalidationState;
+    }
 
     m_paintLayer.layoutObject()->paint(paintInfo, paintOffset);
 }