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

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

Index: third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
diff --git a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
index ad732528ddfe6e0af7c9f139000bd921e7787e46..e7ecebcf9c0744e134e56899a6969f47e760b7b2 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
@@ -49,6 +49,16 @@ public:
     // 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;
 
@@ -64,6 +74,9 @@ private:
     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