GeometryMapper: Support computing visual rects in spaces that are not direct ancestors.

third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h

Index: third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h b/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h
index 2c8daf3979d348d7f5a1693ba165e7521119c174..085c3c8f551b56acdbc7b86d2f55c3f6231221cd 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.h
@@ -17,15 +17,17 @@ class EffectPaintPropertyNode;
 // Represents the combination of transform, clip and effect nodes for a particular coordinate space.
 // See GeometryMapper.
 struct PropertyTreeState {
+    PropertyTreeState() : PropertyTreeState(nullptr, nullptr, nullptr) {}
+
     PropertyTreeState(
         TransformPaintPropertyNode* transform,
         ClipPaintPropertyNode* clip,
         EffectPaintPropertyNode* effect)
     : transform(transform), clip(clip), effect(effect) {}
 
-    TransformPaintPropertyNode* transform;
-    ClipPaintPropertyNode* clip;
-    EffectPaintPropertyNode* effect;
+    RefPtr<TransformPaintPropertyNode> transform;
+    RefPtr<ClipPaintPropertyNode> clip;
+    RefPtr<EffectPaintPropertyNode> effect;
 };
 
 } // namespace blink