use Make instead of Create to return a shared shader

samplecode/SampleBitmapRect.cpp

Index: samplecode/SampleBitmapRect.cpp
diff --git a/samplecode/SampleBitmapRect.cpp b/samplecode/SampleBitmapRect.cpp
index d7eed02ef909094f81c0c84c0ca521b2e857e0dd..490c6a45c312e9a8c8962fc5f5b3e54ef362958c 100644
--- a/samplecode/SampleBitmapRect.cpp
+++ b/samplecode/SampleBitmapRect.cpp
@@ -37,8 +37,8 @@ static void make_bitmap(SkBitmap* bitmap) {
     paint.setAntiAlias(true);
     const SkPoint pts[] = { { 0, 0 }, { SCALAR_SIZE, SCALAR_SIZE } };
     const SkColor colors[] = { SK_ColorWHITE, SK_ColorBLUE };
-    paint.setShader(SkGradientShader::CreateLinear(pts, colors, nullptr, 2,
-                                                   SkShader::kClamp_TileMode))->unref();
+    paint.setShader(SkGradientShader::MakeLinear(pts, colors, nullptr, 2,
+                                                   SkShader::kClamp_TileMode));
     canvas.drawCircle(SCALAR_SIZE/2, SCALAR_SIZE/2, SCALAR_SIZE/2, paint);
 }