Add an API to report debugName in GraphicsLayer

Source/core/platform/graphics/GraphicsLayerClient.h

 /*
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 #ifndef GraphicsLayerClient_h
 #define GraphicsLayerClient_h
 
+#include "wtf/text/WTFString.h"
+
 namespace WebCore {
 
 class FloatPoint;
 class GraphicsContext;
 class GraphicsLayer;
 class IntPoint;
 class IntRect;
 class TransformationMatrix;
 
 enum GraphicsLayerPaintingPhaseFlags {
@@ skipping 31 matching lines @@
 
     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect& inClip) = 0;
     virtual void didCommitChangesForLayer(const GraphicsLayer*) const { }
 
     // Provides current transform (taking transform-origin and animations into account). Input matrix has been
     // initialized to identity already. Returns false if the layer has no transform.
     virtual bool getCurrentTransform(const GraphicsLayer*, TransformationMatrix&) const { return false; }
 
     virtual bool isTrackingRepaints() const { return false; }
 
+    virtual String debugName(const GraphicsLayer* graphicsLayer) { return String(); }
+
 #ifndef NDEBUG
     // RenderLayerBacking overrides this to verify that it is not
     // currently painting contents. An ASSERT fails, if it is.
     // This is executed in GraphicsLayer construction and destruction
     // to verify that we don't create or destroy GraphicsLayers
     // while painting.
     virtual void verifyNotPainting() { }
 #endif
 };
 
 } // namespace WebCore
 
 #endif // GraphicsLayerClient_h