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

gm/tilemodes_scaled.cpp

Index: gm/tilemodes_scaled.cpp
diff --git a/gm/tilemodes_scaled.cpp b/gm/tilemodes_scaled.cpp
index 88a070afb5b627d16a1afd7aab70cdce8bbf0093..a79002b56b31788537da9a7ce7fc823ea6afdac6 100644
--- a/gm/tilemodes_scaled.cpp
+++ b/gm/tilemodes_scaled.cpp
@@ -17,6 +17,7 @@
 
 // effects
 #include "SkGradientShader.h"
+#include "SkUnitMappers.h"
 #include "SkBlurDrawLooper.h"
 
 static void makebm(SkBitmap* bm, SkColorType ct, int w, int h) {
@@ -29,9 +30,16 @@
     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);
 }