Refactor the way PaintArtifactCompositor is attached and used.

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h

 // Copyright 2015 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 PaintArtifactCompositor_h
 #define PaintArtifactCompositor_h
 
 #include "base/memory/ref_counted.h"
 #include "platform/PlatformExport.h"
 #include "wtf/Noncopyable.h"
+#include "wtf/PtrUtil.h"
 #include "wtf/Vector.h"
 #include <memory>
 
 namespace cc {
 class Layer;
 }
 
 namespace gfx {
 class Transform;
 class Vector2dF;
 }
 
 namespace blink {
 
 class PaintArtifact;
 class WebLayer;
 struct PaintChunk;
 
 // Responsible for managing compositing in terms of a PaintArtifact.
 //
 // Owns a subtree of the compositor layer tree, and updates it in response to
 // changes in the paint artifact.
 //
 // PaintArtifactCompositor is the successor to PaintLayerCompositor, reflecting
 // the new home of compositing decisions after paint in Slimming Paint v2.
 class PLATFORM_EXPORT PaintArtifactCompositor {
     WTF_MAKE_NONCOPYABLE(PaintArtifactCompositor);
 public:
-    PaintArtifactCompositor();
     ~PaintArtifactCompositor();
 
+    static std::unique_ptr<PaintArtifactCompositor> create()
+    {
+        return wrapUnique(new PaintArtifactCompositor());
+    }
+
     // Updates the layer tree to match the provided paint artifact.
     void update(const PaintArtifact&);
 
     // The root layer of the tree managed by this object.
     cc::Layer* rootLayer() const { return m_rootLayer.get(); }
 
     // Wraps rootLayer(), so that it can be attached as a child of another
     // WebLayer.
     WebLayer* getWebLayer() const { return m_webLayer.get(); }
 
     // Returns extra information recorded during unit tests.
     // While not part of the normal output of this class, this provides a simple
     // way of locating the layers of interest, since there are still a slew of
     // placeholder layers required.
     struct ExtraDataForTesting {
         Vector<scoped_refptr<cc::Layer>> contentLayers;
     };
     void enableExtraDataForTesting() { m_extraDataForTestingEnabled = true; }
     ExtraDataForTesting* getExtraDataForTesting() const { return m_extraDataForTesting.get(); }
 
 private:
+    PaintArtifactCompositor();
+
     class ContentLayerClientImpl;
 
     // Builds a leaf layer that represents a single paint chunk.
     // Note: cc::Layer API assumes the layer bounds to start at (0, 0) but the bounding box of
     // a paint chunk does not necessarily start at (0, 0) and could even be negative. Internally
     // the generated layer translates the paint chunk to align the bounding box to (0, 0) and
     // return the actual origin of the paint chunk in output parameter layerOffset.
     scoped_refptr<cc::Layer> layerForPaintChunk(const PaintArtifact&, const PaintChunk&, gfx::Vector2dF& layerOffset);
 
     scoped_refptr<cc::Layer> m_rootLayer;
     std::unique_ptr<WebLayer> m_webLayer;
     Vector<std::unique_ptr<ContentLayerClientImpl>> m_contentLayerClients;
 
     bool m_extraDataForTestingEnabled = false;
     std::unique_ptr<ExtraDataForTesting> m_extraDataForTesting;
+    friend class StubChromeClientForSPv2;
 };
 
 } // namespace blink
 
 #endif // PaintArtifactCompositor_h