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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/gm/pictureshadertile.cpp b/gm/pictureshadertile.cpp
index a84e233..30776c3 100644
--- a/gm/pictureshadertile.cpp
+++ b/gm/pictureshadertile.cpp
@@ -121,7 +121,7 @@
             if (tile == SkRect::MakeWH(kPictureSize, kPictureSize)) {
                 // When the tile == picture bounds, exercise the picture + offset path.
                 picturePtr = offsetPicture.get();
-                tilePtr = NULL;
+                tilePtr = nullptr;
             }
 
             fShaders[i].reset(SkShader::CreatePictureShader(picturePtr,