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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/tools/skpdiff/SkDiffContext.cpp b/tools/skpdiff/SkDiffContext.cpp
index 5add0df..8da346e 100644
--- a/tools/skpdiff/SkDiffContext.cpp
+++ b/tools/skpdiff/SkDiffContext.cpp
@@ -22,7 +22,7 @@
 #include "skpdiff_util.h"
 
 SkDiffContext::SkDiffContext() {
-    fDiffers = NULL;
+    fDiffers = nullptr;
     fDifferCount = 0;
 }
 
@@ -58,7 +58,7 @@
     // Delete whatever the last array of differs was
     if (fDiffers) {
         delete[] fDiffers;
-        fDiffers = NULL;
+        fDiffers = nullptr;
         fDifferCount = 0;
     }