add virtual ~Effect()

include/core/SkRefCnt.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkRefCnt_DEFINED
 #define SkRefCnt_DEFINED
 
@@ skipping 226 matching lines @@
  *  classes that match the interface, but have different internal choices: e.g. the hosted class
  *  may have its ref/unref be thread-safe, but that is not assumed/imposed by sk_sp.
  */
 template <typename T> class sk_sp {
     /** Supports safe bool idiom. Obsolete with explicit operator bool. */
     using unspecified_bool_type = T* sk_sp::*;
 public:
     sk_sp() : fPtr(nullptr) {}
     sk_sp(std::nullptr_t) : fPtr(nullptr) {}
 
+    // TODO: for all these constructors and assignments that take <typename U>,
+    // can we add static assertions that sk_sp<T> -> sk_sp<U> doesn't slice
+    // (something like, T has a trivial destructor or U's destructor is virtual)?
+

[bungeman-skia, 2016/03/07 19:29:45]

Putting this here is a bit over constrained. sk_sp doesn't call 'delete', it
calls 'unref'. It sounds a bit dumb, but 'unref' in the base class could figure
out what derived class it was, downcast, and then properly delete. I think it
really is up to the individual class implementation to make sure that it's
properly written in this regard.

[mtklein_C, 2016/03/07 19:40:46]

Agreed.  Now gone.

     /**
      *  Shares the underlying object by calling ref(), so that both the argument and the newly
      *  created sk_sp both have a reference to it.
      */
     sk_sp(const sk_sp<T>& that) : fPtr(SkSafeRef(that.get())) {}
     template <typename U,
               typename = skstd::enable_if_t<skstd::is_convertible<U*, T*>::value>>
     sk_sp(const sk_sp<U>& that) : fPtr(SkSafeRef(that.get())) {}
 
     /**
@@ skipping 99 matching lines @@
 private:
     T*  fPtr;
 };
 
 template <typename T, typename... Args>
 sk_sp<T> sk_make_sp(Args&&... args) {
     return sk_sp<T>(new T(std::forward<Args>(args)...));
 }
 
 #endif