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

Review URL: https://codereview.chromium.org/1316233002
diff --git a/gm/shallowgradient.cpp b/gm/shallowgradient.cpp
index 276ec14..b2a34f3 100644
--- a/gm/shallowgradient.cpp
+++ b/gm/shallowgradient.cpp
@@ -12,13 +12,13 @@
 
 static SkShader* shader_linear(const SkColor colors[], int count, const SkSize& size) {
     SkPoint pts[] = { { 0, 0 }, { size.width(), size.height() } };
-    return SkGradientShader::CreateLinear(pts, colors, NULL, count,
+    return SkGradientShader::CreateLinear(pts, colors, nullptr, count,
                                           SkShader::kClamp_TileMode);
 }
 
 static SkShader* shader_radial(const SkColor colors[], int count, const SkSize& size) {
     SkPoint center = { size.width()/2, size.height()/2 };
-    return SkGradientShader::CreateRadial(center, size.width()/2, colors, NULL, count,
+    return SkGradientShader::CreateRadial(center, size.width()/2, colors, nullptr, count,
                                           SkShader::kClamp_TileMode);
 }
 
@@ -26,13 +26,13 @@
     SkPoint center = { size.width()/2, size.height()/2 };
     return SkGradientShader::CreateTwoPointConical(center, size.width()/64,
                                                    center, size.width()/2,
-                                                   colors, NULL, count,
+                                                   colors, nullptr, count,
                                                    SkShader::kClamp_TileMode);
 }
 
 static SkShader* shader_sweep(const SkColor colors[], int count, const SkSize& size) {
     return SkGradientShader::CreateSweep(size.width()/2, size.height()/2,
-                                         colors, NULL, count);
+                                         colors, nullptr, count);
 }
 
 class ShallowGradientGM : public skiagm::GM {