Fix up all the easy virtual ... SK_OVERRIDE cases.

include/core/SkWeakRefCnt.h

Index: include/core/SkWeakRefCnt.h
diff --git a/include/core/SkWeakRefCnt.h b/include/core/SkWeakRefCnt.h
index 210dcc9f1c7bd6bdbefd2a375fb6851ef2ffdd02..3eb8ea5ca5622f2f659c0d347862220e6e269c23 100644
--- a/include/core/SkWeakRefCnt.h
+++ b/include/core/SkWeakRefCnt.h
@@ -147,7 +147,7 @@ private:
         on the object and releases the implicit weak reference held
         collectively by the strong references.
     */
-    virtual void internal_dispose() const SK_OVERRIDE {
+    void internal_dispose() const SK_OVERRIDE {
         weak_dispose();
         weak_unref();
     }