move SkChecksum and SkEmptyShader to private

src/effects/gradients/SkGradientShader.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGradientShaderPriv.h"
 #include "SkLinearGradient.h"
 #include "SkRadialGradient.h"
@@ skipping 680 matching lines @@
     str->append(" ");
     str->append(gTileModeName[fTileMode]);
 
     this->INHERITED::toString(str);
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
 
-#include "SkEmptyShader.h"
-
 // assumes colors is SkColor* and pos is SkScalar*
 #define EXPAND_1_COLOR(count)               \
     SkColor tmp[2];                         \
     do {                                    \
         if (1 == count) {                   \
             tmp[0] = tmp[1] = colors[0];    \
             colors = tmp;                   \
             pos = NULL;                     \
             count = 2;                      \
         }                                   \
@@ skipping 70 matching lines @@
                                                   const SkColor colors[],
                                                   const SkScalar pos[],
                                                   int colorCount,
                                                   SkShader::TileMode mode,
                                                   uint32_t flags,
                                                   const SkMatrix* localMatrix) {
     if (startRadius < 0 || endRadius < 0 || NULL == colors || colorCount < 1) {
         return NULL;
     }
     if (start == end && startRadius == endRadius) {
-        return SkNEW(SkEmptyShader);
+        return SkShader::CreateEmptyShader();
     }
 
     EXPAND_1_COLOR(colorCount);
 
     bool flipGradient = startRadius > endRadius;
 
     SkGradientShaderBase::Descriptor desc;
 
     if (!flipGradient) {
         desc_init(&desc, colors, pos, colorCount, mode, flags);
@@ skipping 345 matching lines @@
             (*stops)[i] = stop;
             stop = i < outColors - 1 ? stop + random->nextUScalar1() * (1.f - stop) : 1.f;
         }
     }
     *tm = static_cast<SkShader::TileMode>(random->nextULessThan(SkShader::kTileModeCount));
 
     return outColors;
 }
 
 #endif