move SkChecksum and SkEmptyShader to private

tests/GradientTest.cpp

 /*
  * Copyright 2011 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 "SkColorShader.h"
-#include "SkEmptyShader.h"
 #include "SkGradientShader.h"
 #include "SkShader.h"
 #include "SkTemplates.h"
 #include "Test.h"
 
 struct GradRec {
     int             fColorCount;
     const SkColor*  fColors;
     const SkScalar* fPos;
     const SkPoint*  fPoint;   // 2
@@ skipping 15 matching lines @@
         REPORTER_ASSERT(reporter,
                         !memcmp(info->fColors, fColors, fColorCount * sizeof(SkColor)));
         REPORTER_ASSERT(reporter,
                         !memcmp(info->fColorOffsets, fPos, fColorCount * sizeof(SkScalar)));
         REPORTER_ASSERT(reporter, fTileMode == info->fTileMode);
     }
 };
 
 
 static void none_gradproc(skiatest::Reporter* reporter, const GradRec&) {
-    SkAutoTUnref<SkShader> s(new SkEmptyShader);
+    SkAutoTUnref<SkShader> s(SkShader::CreateEmptyShader());
     REPORTER_ASSERT(reporter, SkShader::kNone_GradientType == s->asAGradient(NULL));
 }
 
 static void color_gradproc(skiatest::Reporter* reporter, const GradRec& rec) {
     SkAutoTUnref<SkShader> s(new SkColorShader(rec.fColors[0]));
     REPORTER_ASSERT(reporter, SkShader::kColor_GradientType == s->asAGradient(NULL));
 
     SkShader::GradientInfo info;
     info.fColors = NULL;
     info.fColorCount = 0;
@@ skipping 130 matching lines @@
 
     for (size_t i = 0; i < SK_ARRAY_COUNT(gProcs); ++i) {
         gProcs[i](reporter, rec);
     }
 }
 
 DEF_TEST(Gradient, reporter) {
     TestGradientShaders(reporter);
     TestConstantGradient(reporter);
 }