[SPv2] Begin to convert the Blink transform tree to cc.

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"
@@ skipping 31 matching lines @@
     // 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;

[jbroman, 2016/06/27 20:34:29]

I'm not thrilled with this, but I need some way to figure out which layers to
look at, and this seemed more reasonable to me than baking assumptions about
where exactly when the synthetic layers get attached into the unit tests.

+    };
+    void enableExtraDataForTesting() { m_extraDataForTestingEnabled = true; }
+    ExtraDataForTesting* getExtraDataForTesting() const { return m_extraDataForTesting.get(); }
+
 private:
     class ContentLayerClientImpl;
 
     void updateInLayerListMode(const PaintArtifact&);
 
     // 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;
 };
 
 } // namespace blink
 
 #endif // PaintArtifactCompositor_h