switch surface to sk_sp

src/image/SkImage_Generator.cpp

Index: src/image/SkImage_Generator.cpp
diff --git a/src/image/SkImage_Generator.cpp b/src/image/SkImage_Generator.cpp
index f8af12a612d22272935fc884196d4c6e01bd63ad..44dd7b11f83b8dfaff8d37a35a2e48c0d1201a09 100644
--- a/src/image/SkImage_Generator.cpp
+++ b/src/image/SkImage_Generator.cpp
@@ -79,7 +79,7 @@ sk_sp<SkImage> SkImage_Generator::onMakeSubset(const SkIRect& subset) const {
 
     const SkImageInfo info = SkImageInfo::MakeN32(subset.width(), subset.height(),
                                       this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
-    SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
+    auto surface(SkSurface::MakeRaster(info));
     if (!surface) {
         return nullptr;
     }