Reuse cc::PictureLayers when possible for SPv2.

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 34b6e2f9f104ae073f907d5b8bce778bf9b087af..abcdd99c33b9c6120322a8729d77c9146ebb4913 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
@@ -74,11 +74,16 @@ private:
     // 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> layerForPaintChunk(const PaintArtifact&, const PaintChunk&, gfx::Vector2dF& layerOffset,
+        Vector<std::unique_ptr<ContentLayerClientImpl>>& newContentLayerClients);
+
+    // Finds a client among the current vector of clients that matches the paint chunk's id,
+    // or otherwise allocates a new one.
+    std::unique_ptr<ContentLayerClientImpl> clientForPaintChunk(const PaintChunk&);
 
     scoped_refptr<cc::Layer> m_rootLayer;
     std::unique_ptr<WebLayer> m_webLayer;
-    Vector<std::unique_ptr<ContentLayerClientImpl>> m_contentLayerClients;
+    Vector<std::unique_ptr<ContentLayerClientImpl>> m_currentContentLayerClients;

[pdr., 2016/09/21 22:45:12]

Nit: revert this back to m_contentLayerClients

[chrishtr, 2016/09/22 16:51:33]

Done.

 
     bool m_extraDataForTestingEnabled = false;
     std::unique_ptr<ExtraDataForTesting> m_extraDataForTesting;