DCHECK that paint properties are never null

third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
index 33b273b60daf80594f2ac0e0269b02351be61adc..f5e4c59d76cc3ef9ab7264840baf18c76d0c344c 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintChunker.cpp
@@ -26,6 +26,15 @@ void PaintChunker::updateCurrentPaintChunkProperties(
 bool PaintChunker::incrementDisplayItemIndex(const DisplayItem& item) {
   DCHECK(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
+  // Property nodes should never be null because they should either be set to
+  // properties created by a LayoutObject/FrameView, or be set to a non-null
+  // root node. If these DCHECKs are hit we are missing a call to update the
+  // properties. See: ScopedPaintChunkProperties.
+  DCHECK(m_currentProperties.transform);
+  DCHECK(m_currentProperties.clip);
+  DCHECK(m_currentProperties.effect);
+  DCHECK(m_currentProperties.scroll);
+
   ItemBehavior behavior;
   Optional<PaintChunk::Id> newChunkId;
   if (DisplayItem::isForeignLayerType(item.getType())) {