Revert of Remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/) (https://codereview.chromium.org/288343009/)

Reason for revert:
required blink change failed to land

Original issue's description:
> Remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/)
>
> This reverts commit dd50c83b5b34dab3a077741861b50ed1f2bc6b8f.
>
> BUG=skia:
>
> Committed: http://code.google.com/p/skia/source/detail?r=14830

R=scroggo@google.com, reed@google.com
TBR=reed@google.com, scroggo@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/296823008

git-svn-id: http://skia.googlecode.com/svn/trunk@14838 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleAll.cpp b/samplecode/SampleAll.cpp
index 92fe258..ea1f143 100644
--- a/samplecode/SampleAll.cpp
+++ b/samplecode/SampleAll.cpp
@@ -36,6 +36,7 @@
 #include "SkRandom.h"
 #include "SkTransparentShader.h"
 #include "SkTypeface.h"
+#include "SkUnitMappers.h"
 #include "SkUtils.h"
 #include "SkXfermode.h"
 
@@ -367,8 +368,10 @@
         SkScalar* linearPos = NULL;
         int linearCount = 2;
         SkShader::TileMode linearMode = SkShader::kMirror_TileMode;
+        SkUnitMapper* linearMapper = new SkDiscreteMapper(3);
+        SkAutoUnref unmapLinearMapper(linearMapper);
         SkShader* linear = SkGradientShader::CreateLinear(linearPoints,
-            linearColors, linearPos, linearCount, linearMode);
+            linearColors, linearPos, linearCount, linearMode, linearMapper);
 
         SkPoint radialCenter = { SkIntToScalar(25), SkIntToScalar(25) };
         SkScalar radialRadius = SkIntToScalar(25);
@@ -376,9 +379,11 @@
         SkScalar radialPos[] = { 0, SkIntToScalar(3) / 5, SkIntToScalar(1)};
         int radialCount = 3;
         SkShader::TileMode radialMode = SkShader::kRepeat_TileMode;
+        SkUnitMapper* radialMapper = new SkCosineMapper();
+        SkAutoUnref unmapRadialMapper(radialMapper);
         SkShader* radial = SkGradientShader::CreateRadial(radialCenter,
             radialRadius, radialColors, radialPos, radialCount,
-            radialMode);
+            radialMode, radialMapper);
 
         SkTransparentShader* transparentShader = new SkTransparentShader();
         SkEmbossMaskFilter::Light light;