Fix clang 12 Wsuggest-override and Wsuggest-destructor-override


Change-Id: Ic44e24057b95bb014504f02a736fb4341afc8971
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/304856
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
diff --git a/tools/viewer/SlideDir.cpp b/tools/viewer/SlideDir.cpp
index 017febe..5cce6b1 100644
--- a/tools/viewer/SlideDir.cpp
+++ b/tools/viewer/SlideDir.cpp
@@ -26,7 +26,6 @@
 
 class SlideDir::Animator : public SkRefCnt {
 public:
-    virtual ~Animator() = default;
     Animator(const Animator&) = delete;
     Animator& operator=(const Animator&) = delete;
 
@@ -195,7 +194,7 @@
     }
 
 protected:
-    void onTick(float t) {
+    void onTick(float t) override {
         if (!this->isAnimating())
             return;