[SPv2] Refactor PaintArtifactorCompositor root node creation

third_party/WebKit/Source/platform/testing/TestPaintArtifact.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TestPaintArtifact_h
 #define TestPaintArtifact_h
 
 #include "base/memory/ref_counted.h"
 #include "platform/graphics/Color.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 #include "platform/graphics/paint/PaintArtifact.h"
+#include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "wtf/Allocator.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/Vector.h"
 #include <memory>
 
 namespace cc {
 class Layer;
 }
 
 namespace blink {
 
 class ClipPaintPropertyNode;
 class EffectPaintPropertyNode;
 class FloatRect;
 class PaintArtifact;
-class ScrollPaintPropertyNode;
 class TransformPaintPropertyNode;
 
 // Useful for quickly making a paint artifact in unit tests.
 // Must remain in scope while the paint artifact is used, because it owns the
 // display item clients.
 //
 // Usage:
 //   TestPaintArtifact artifact;
 //   artifact.chunk(paintProperties)
 //       .rectDrawing(bounds, color)
 //       .rectDrawing(bounds2, color2);
 //   artifact.chunk(otherPaintProperties)
 //       .rectDrawing(bounds3, color3);
 //   doSomethingWithArtifact(artifact);
 class TestPaintArtifact {
   STACK_ALLOCATED();
 
  public:
   TestPaintArtifact();
   ~TestPaintArtifact();
 
   // Add to the artifact.
-  TestPaintArtifact& chunk(PassRefPtr<TransformPaintPropertyNode>,
-                           PassRefPtr<ClipPaintPropertyNode>,
-                           PassRefPtr<EffectPaintPropertyNode>,
-                           PassRefPtr<ScrollPaintPropertyNode> = nullptr);
+  TestPaintArtifact& chunk(
+      PassRefPtr<TransformPaintPropertyNode>,
+      PassRefPtr<ClipPaintPropertyNode>,
+      PassRefPtr<EffectPaintPropertyNode>,
+      PassRefPtr<ScrollPaintPropertyNode> = ScrollPaintPropertyNode::root());
   TestPaintArtifact& chunk(const PaintChunkProperties&);
   TestPaintArtifact& rectDrawing(const FloatRect& bounds, Color);
   TestPaintArtifact& foreignLayer(const FloatPoint&,
                                   const IntSize&,
                                   scoped_refptr<cc::Layer>);
 
   // Can't add more things once this is called.
   const PaintArtifact& build();
 
  private:
   class DummyRectClient;
   Vector<std::unique_ptr<DummyRectClient>> m_dummyClients;
 
   // Exists if m_built is false.
   DisplayItemList m_displayItemList;
   Vector<PaintChunk> m_paintChunks;
 
   // Exists if m_built is true.
   PaintArtifact m_paintArtifact;
 
   bool m_built;
 };
 
 }  // namespace blink
 
 #endif  // TestPaintArtifact_h