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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/samplecode/SamplePathClip.cpp b/samplecode/SamplePathClip.cpp
index 494debf..27f1f30 100644
--- a/samplecode/SamplePathClip.cpp
+++ b/samplecode/SamplePathClip.cpp
@@ -76,7 +76,7 @@
 
     bool onClick(Click* click) override {
         fCenter.set(click->fCurr.fX, click->fCurr.fY);
-        this->inval(NULL);
+        this->inval(nullptr);
         return false;
     }