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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/samplecode/SampleTextAlpha.cpp b/samplecode/SampleTextAlpha.cpp
index f344021..d8fd104 100644
--- a/samplecode/SampleTextAlpha.cpp
+++ b/samplecode/SampleTextAlpha.cpp
@@ -65,7 +65,7 @@
             paint.setTextSize(SkIntToScalar(ps));
             paint.setTextSize(SkIntToScalar(24));
             canvas->drawText(str, strlen(str), x, y, paint);
-            y += paint.getFontMetrics(NULL);
+            y += paint.getFontMetrics(nullptr);
         }
     }
 
@@ -81,7 +81,7 @@
             y = 255;
         }
         fByte = y;
-        this->inval(NULL);
+        this->inval(nullptr);
         return true;
     }