Revert of remove unused (by clients) SkUnitMapper

experimental/SkiaExamples/HelloSkiaExample.cpp

Index: experimental/SkiaExamples/HelloSkiaExample.cpp
diff --git a/experimental/SkiaExamples/HelloSkiaExample.cpp b/experimental/SkiaExamples/HelloSkiaExample.cpp
index 6fd2624c18b0e5e97f9f3ff69b5abfe716f6cbce..0b6c790460eb54900b859e839f73275a0ead41ee 100644
--- a/experimental/SkiaExamples/HelloSkiaExample.cpp
+++ b/experimental/SkiaExamples/HelloSkiaExample.cpp
@@ -13,6 +13,7 @@
 #include "SkDraw.h"
 #include "SkGradientShader.h"
 #include "SkGraphics.h"
+#include "SkUnitMappers.h"
 
 class HelloSkia : public SkExample {
 public:
@@ -49,9 +50,12 @@
             };
             SkColor linearColors[] = {SK_ColorGREEN, SK_ColorBLACK};
 
+            SkUnitMapper* linearMapper = new SkDiscreteMapper(100);
+            SkAutoUnref lm_deleter(linearMapper);
+
             SkShader* shader = SkGradientShader::CreateLinear(
                     linearPoints, linearColors, NULL, 2,
-                    SkShader::kMirror_TileMode);
+                    SkShader::kMirror_TileMode, linearMapper);
             SkAutoUnref shader_deleter(shader);
 
             paint.setShader(shader);