Refactor the way PaintArtifactCompositor is attached and used.

third_party/WebKit/Source/core/paint/StubChromeClientForSPv2.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 StubChromeClientForSPv2_h
 #define StubChromeClientForSPv2_h
 
 #include "core/loader/EmptyClients.h"
-#include "platform/graphics/compositing/PaintArtifactCompositor.h"
 #include "platform/testing/WebLayerTreeViewImplForTesting.h"
 
 namespace blink {
 
 // A simple ChromeClient implementation which forwards painted artifacts to a
 // PaintArtifactCompositor attached to a testing WebLayerTreeView, and permits
 // simple analysis of the results.
 class StubChromeClientForSPv2 : public EmptyChromeClient {
 public:
-    StubChromeClientForSPv2() : m_layerTreeView()
-    {
-        m_layerTreeView.setRootLayer(*m_paintArtifactCompositor.getWebLayer());
-    }
+    StubChromeClientForSPv2() : m_layerTreeView() { }
 
     bool hasLayer(const WebLayer& layer) { return m_layerTreeView.hasLayer(layer); }
 
-    // ChromeClient
-    void didPaint(const PaintArtifact& artifact) override
+    void attachRootLayer(WebLayer* layer, LocalFrame* localRoot) override
     {
-        m_paintArtifactCompositor.update(artifact);
+        m_layerTreeView.setRootLayer(*layer);
     }
 
 private:
     WebLayerTreeViewImplForTesting m_layerTreeView;
-    PaintArtifactCompositor m_paintArtifactCompositor;
 };
 
 } // namespace blink
 
 #endif // StubChromeClientForSPv2_h