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/drawatlascolor.cpp b/gm/drawatlascolor.cpp
index 85a7a94..e8fd236 100644
--- a/gm/drawatlascolor.cpp
+++ b/gm/drawatlascolor.cpp
@@ -19,9 +19,9 @@
     const int kBlockSize = atlasSize/2;
 
     SkImageInfo info = SkImageInfo::MakeN32Premul(atlasSize, atlasSize);
-    SkAutoTUnref<SkSurface> surface(caller->newSurface(info));
+    auto surface(caller->makeSurface(info));
     if (nullptr == surface) {
-        surface.reset(SkSurface::NewRaster(info));
+        surface = SkSurface::MakeRaster(info);
     }
     SkCanvas* canvas = surface->getCanvas();