Revert of Remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/)

gm/shaderbounds.cpp

Index: gm/shaderbounds.cpp
diff --git a/gm/shaderbounds.cpp b/gm/shaderbounds.cpp
index f82985bf520c8fe052de8d737c4b42cb6bc802d9..f0b8b9781da340e8952fec41d310cd5702c9490c 100644
--- a/gm/shaderbounds.cpp
+++ b/gm/shaderbounds.cpp
@@ -19,7 +19,7 @@
     colors[1] = SK_ColorYELLOW;
   }
   return SkGradientShader::CreateLinear(pts, colors, NULL, 2,
-                                        SkShader::kClamp_TileMode, 0, &localMatrix);
+                                        SkShader::kClamp_TileMode, NULL, 0, &localMatrix);
 }
 
 ///////////////////////////////////////////////////////////////////////////////