switch surface to sk_sp

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1817383002
CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac-Clang-x86_64-Release-CMake-Trybot

Review URL: https://codereview.chromium.org/1817383002
diff --git a/gm/color4f.cpp b/gm/color4f.cpp
index ec9bbcb..7704dee 100644
--- a/gm/color4f.cpp
+++ b/gm/color4f.cpp
@@ -77,7 +77,7 @@
     for (auto profile : profiles) {
         const SkImageInfo info = SkImageInfo::Make(1024, 100, kN32_SkColorType, kPremul_SkAlphaType,
                                                    profile);
-        SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
+        auto surface(SkSurface::MakeRaster(info));
         surface->getCanvas()->drawPaint(bg);
         draw_into_canvas(surface->getCanvas());
         surface->draw(canvas, 0, 0, nullptr);