API change to allow for NormalSource selection at the user level.

samplecode/SampleLitAtlas.cpp

Index: samplecode/SampleLitAtlas.cpp
diff --git a/samplecode/SampleLitAtlas.cpp b/samplecode/SampleLitAtlas.cpp
index f1d67e5c7933b0050e491e51c0d974898e810268..058ac5d05a2befdd7e3d2293b84f2657807846d7 100644
--- a/samplecode/SampleLitAtlas.cpp
+++ b/samplecode/SampleLitAtlas.cpp
@@ -132,8 +132,10 @@ protected:
             SkVector invNormRotation = { m[SkMatrix::kMScaleX], m[SkMatrix::kMSkewY] };
             SkASSERT(SkScalarNearlyEqual(invNormRotation.lengthSqd(), SK_Scalar1));
 
-            paint.setShader(SkLightingShader::Make(fAtlas, fAtlas, fLights,
-                                                   invNormRotation, &diffMat, &normalMat));
+            auto normalSource = SkLightingShader::NormalMapSource::Make(fAtlas, invNormRotation,
+                                                                        &normalMat);
+            paint.setShader(SkLightingShader::Make(fAtlas, fLights, &diffMat,
+                                                   std::move(normalSource)));
 
             canvas->save();
                 canvas->setMatrix(m);