Move SkTypeface to sk_sp.

gm/fontcache.cpp

Index: gm/fontcache.cpp
diff --git a/gm/fontcache.cpp b/gm/fontcache.cpp
index 30f8892c78f88c1a93ae71deade77dc8d6f061b5..c4af48930428fde367f21054b702ef3905537f7a 100644
--- a/gm/fontcache.cpp
+++ b/gm/fontcache.cpp
@@ -20,15 +20,7 @@ static SkScalar draw_string(SkCanvas* canvas, const SkString& text, SkScalar x,
 
 class FontCacheGM : public skiagm::GM {
 public:
-    FontCacheGM() {
-        fTypefaces[0] = nullptr;
-        fTypefaces[1] = nullptr;
-    }
-
-    virtual ~FontCacheGM() {
-        SkSafeUnref(fTypefaces[0]);
-        SkSafeUnref(fTypefaces[1]);
-    }
+    FontCacheGM() {}
 
 protected:
     SkString onShortName() override {
@@ -76,7 +68,7 @@ protected:
     }
 
 private:
-    SkTypeface* fTypefaces[2];
+    sk_sp<SkTypeface> fTypefaces[2];
     typedef GM INHERITED;
 };