Add optional debugging output of what paint chunks go into what layers.

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 fef6b35ba364bfc6666d0c2b16f696a2527e2cc6..c9eae71af5ea769a67f70b1894169b66191d4bc1 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
@@ -48,9 +48,13 @@ class PLATFORM_EXPORT PaintArtifactCompositor {
   }
 
   // Updates the layer tree to match the provided paint artifact.
+  // If |storeDebugInfo| is true, stores detailed debugging information in
+  // the layers that will be output as part of a call to layersAsJSON,
+  // if LayerTreeIncludesDebugInfo is specified.

[wkorman, 2016/12/15 21:36:05]

This read to me as if the debug info will only be stored if storeDebugInfo is
true *and* the LayerTreeIncludesDebugInfo flag is specified. Add parens around
the second part, or could just stay "...detailed debugging info in the layers
for use by layersAsJSON as needed."

[chrishtr, 2016/12/15 22:35:11]

Done.

   void update(
       const PaintArtifact&,
-      RasterInvalidationTrackingMap<const PaintChunk>* paintChunkInvalidations);
+      RasterInvalidationTrackingMap<const PaintChunk>* paintChunkInvalidations,
+      bool storeDebugInfo);
 
   // The root layer of the tree managed by this object.
   cc::Layer* rootLayer() const { return m_rootLayer.get(); }
@@ -93,7 +97,8 @@ class PLATFORM_EXPORT PaintArtifactCompositor {
       const PaintChunk&,
       gfx::Vector2dF& layerOffset,
       Vector<std::unique_ptr<ContentLayerClientImpl>>& newContentLayerClients,
-      RasterInvalidationTracking*);
+      RasterInvalidationTracking*,
+      bool storeDebugInfo);
 
   // Finds a client among the current vector of clients that matches the paint
   // chunk's id, or otherwise allocates a new one.