Compositor thread plumbing for layout rectangle debug info.

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 9af3dea7c7de4f3165334cc6da8e3bfbe36ce105..4a156285588f194fd057e71509e469893eb5ddb7 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -38,6 +38,12 @@ namespace gfx {
 class BoxF;
 }
 
+namespace base {
+namespace debug {
+class ConvertableToTraceFormat;
+}
+}
+
 namespace cc {
 
 class Animation;
@@ -356,6 +362,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   virtual void OnOutputSurfaceCreated() {}
 
   virtual std::string DebugName();
+  virtual base::debug::ConvertableToTraceFormat* TakeDebugInfo();
 
   void SetLayerClient(LayerClient* client) { client_ = client; }