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

gm/tilemodes.cpp

Index: gm/tilemodes.cpp
diff --git a/gm/tilemodes.cpp b/gm/tilemodes.cpp
index 99d3a4708b1c48c3a51467468a87c19b3b7d058c..e04c52ae0fd6e5423ed9016e254e860bb92d20df 100644
--- a/gm/tilemodes.cpp
+++ b/gm/tilemodes.cpp
@@ -16,6 +16,7 @@
 
 // effects
 #include "SkGradientShader.h"
+#include "SkUnitMappers.h"
 #include "SkBlurDrawLooper.h"
 
 static void makebm(SkBitmap* bm, SkColorType ct, int w, int h) {
@@ -28,9 +29,16 @@
     SkScalar    pos[] = { 0, SK_Scalar1/2, SK_Scalar1 };
     SkPaint     paint;
 
+    SkUnitMapper*   um = NULL;
+
+    um = new SkCosineMapper;
+//    um = new SkDiscreteMapper(12);
+
+    SkAutoUnref au(um);
+
     paint.setDither(true);
     paint.setShader(SkGradientShader::CreateLinear(pts, colors, pos,
-                SK_ARRAY_COUNT(colors), SkShader::kClamp_TileMode))->unref();
+                SK_ARRAY_COUNT(colors), SkShader::kClamp_TileMode, um))->unref();
     canvas.drawPaint(paint);
 }