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

gm/gradient_matrix.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkColor.h"
 #include "SkGradientShader.h"
@@ skipping 45 matching lines @@
 };
 
 // These define the pixels allocated to each gradient image.
 static const SkScalar TESTGRID_X = SkIntToScalar(200);
 static const SkScalar TESTGRID_Y = SkIntToScalar(200);
 
 static const int IMAGES_X = 4;             // number of images per row
 
 static SkShader* make_linear_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
     return SkGradientShader::CreateLinear(pts, gColors, NULL, SK_ARRAY_COUNT(gColors),
-                                          SkShader::kClamp_TileMode, 0, &localMatrix);
+                                          SkShader::kClamp_TileMode, NULL, 0, &localMatrix);
 }
 
 static SkShader* make_radial_gradient(const SkPoint pts[2], const SkMatrix& localMatrix) {
     SkPoint center;
     center.set(SkScalarAve(pts[0].fX, pts[1].fX),
                SkScalarAve(pts[0].fY, pts[1].fY));
     float radius = (center - pts[0]).length();
     return SkGradientShader::CreateRadial(center, radius, gColors, NULL, SK_ARRAY_COUNT(gColors),
-                                          SkShader::kClamp_TileMode, 0, &localMatrix);
+                                          SkShader::kClamp_TileMode, NULL, 0, &localMatrix);
 }
 
 static void draw_gradients(SkCanvas* canvas,
                            SkShader* (*makeShader)(const SkPoint[2], const SkMatrix&),
                            const SkPoint ptsArray[][2], int numImages) {
     // Use some nice prime numbers for the rectangle and matrix with
     // different scaling along the x and y axes (which is the bug this
     // test addresses, where incorrect order of operations mixed up the axes)
     SkRect rectGrad = {
         SkIntToScalar(43),  SkIntToScalar(61),
@@ skipping 55 matching lines @@
         draw_gradients(canvas, &make_radial_gradient,
                       radialPts, SK_ARRAY_COUNT(radialPts));
     }
 
 private:
     typedef GM INHERITED;
 };
 
 DEF_GM( return new GradientMatrixGM; )
 }