Add const to BindStateBase to align RefCounted constness

base/bind_internal.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_BIND_INTERNAL_H_
 #define BASE_BIND_INTERNAL_H_
 
 #include <stddef.h>
 
 #include <tuple>
@@ skipping 452 matching lines @@
                      ForwardFunctor&& functor,
                      ForwardBoundArgs&&... bound_args)
       : BindStateBase(invoke_func, &Destroy),
         functor_(std::forward<ForwardFunctor>(functor)),
         bound_args_(std::forward<ForwardBoundArgs>(bound_args)...) {
     DCHECK(!IsNull(functor_));
   }
 
   ~BindState() {}
 
-  static void Destroy(BindStateBase* self) {
-    delete static_cast<BindState*>(self);
+  static void Destroy(const BindStateBase* self) {
+    delete static_cast<const BindState*>(self);
   }
 };
 
 // Used to implement MakeBindStateType.
 template <bool is_method, typename Functor, typename... BoundArgs>
 struct MakeBindStateTypeImpl;
 
 template <typename Functor, typename... BoundArgs>
 struct MakeBindStateTypeImpl<false, Functor, BoundArgs...> {
   static_assert(!HasRefCountedTypeAsRawPtr<BoundArgs...>::value,
@@ skipping 38 matching lines @@
 
 // Returns a RunType of bound functor.
 // E.g. MakeUnboundRunType<R(A, B, C), A, B> is evaluated to R(C).
 template <typename Functor, typename... BoundArgs>
 using MakeUnboundRunType =
     typename internal::MakeUnboundRunTypeImpl<Functor, BoundArgs...>::Type;
 
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_