Style Change: NULL->nullptr
DOCS_PREVIEW= https://skia.org/?cl=1316233002

Review URL: https://codereview.chromium.org/1316233002
diff --git a/samplecode/SampleClamp.cpp b/samplecode/SampleClamp.cpp
index 2368ab2..e319a56 100644
--- a/samplecode/SampleClamp.cpp
+++ b/samplecode/SampleClamp.cpp
@@ -16,7 +16,7 @@
 static SkShader* make_linear() {
     SkPoint pts[] = { 0, 0, SK_Scalar1/500, SK_Scalar1/500 };
     SkColor colors[] = { SK_ColorRED, SK_ColorBLUE };
-    return SkGradientShader::CreateLinear(pts, colors, NULL, 2,
+    return SkGradientShader::CreateLinear(pts, colors, nullptr, 2,
                                           SkShader::kClamp_TileMode);
 }