use Make instead of Create to return a shared shader

tools/sk_tool_utils.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "sk_tool_utils.h"
 #include "sk_tool_utils_flags.h"
 
@@ skipping 160 matching lines @@
 void write_pixels(SkCanvas* canvas, const SkBitmap& bitmap, int x, int y,
                   SkColorType colorType, SkAlphaType alphaType) {
     SkBitmap tmp(bitmap);
     tmp.lockPixels();
 
     const SkImageInfo info = SkImageInfo::Make(tmp.width(), tmp.height(), colorType, alphaType);
 
     canvas->writePixels(info, tmp.getPixels(), tmp.rowBytes(), x, y);
 }
 
-SkShader* create_checkerboard_shader(SkColor c1, SkColor c2, int size) {
+sk_sp<SkShader> create_checkerboard_shader(SkColor c1, SkColor c2, int size) {
     SkBitmap bm;
     bm.allocN32Pixels(2 * size, 2 * size);
     bm.eraseColor(c1);
     bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
     bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
-    return SkShader::CreateBitmapShader(
+    return SkShader::MakeBitmapShader(
             bm, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
 }
 
 SkBitmap create_checkerboard_bitmap(int w, int h, SkColor c1, SkColor c2, int checkSize) {
     SkBitmap bitmap;
     bitmap.allocN32Pixels(w, h);
     SkCanvas canvas(bitmap);
 
     sk_tool_utils::draw_checkerboard(&canvas, c1, c2, checkSize);
     return bitmap;
 }
 
 void draw_checkerboard(SkCanvas* canvas, SkColor c1, SkColor c2, int size) {
     SkPaint paint;
-    paint.setShader(create_checkerboard_shader(c1, c2, size))->unref();
+    paint.setShader(create_checkerboard_shader(c1, c2, size));
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
     canvas->drawPaint(paint);
 }
 
 SkBitmap create_string_bitmap(int w, int h, SkColor c, int x, int y,
                               int textSize, const char* str) {
     SkBitmap bitmap;
     bitmap.allocN32Pixels(w, h);
     SkCanvas canvas(bitmap);
 
@@ skipping 224 matching lines @@
     for (int y = 0; y < src.height(); ++y) {
         for (int x = 0; x < src.width(); ++x) {
             *dst.getAddr32(x, y) = blur_pixel(src, x, y, kernel.get(), wh);
         }
     }
  
     return dst;
 }
 
 }  // namespace sk_tool_utils