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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/gm/textblobuseaftergpufree.cpp b/gm/textblobuseaftergpufree.cpp
index 363cd2f..91681b8 100644
--- a/gm/textblobuseaftergpufree.cpp
+++ b/gm/textblobuseaftergpufree.cpp
@@ -31,7 +31,7 @@
 
     void onDraw(SkCanvas* canvas) override {
         // This GM exists to test a specific feature of the GPU backend.
-        if (NULL == canvas->getGrContext()) {
+        if (nullptr == canvas->getGrContext()) {
             this->drawGpuOnlyMessage(canvas);
             return;
         }