Add a PassScopedPtr into base/memory.

base/callback_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.
 
 // This file contains utility functions and classes that help the
 // implementation, and management of the Callback objects.
 
 #ifndef BASE_CALLBACK_INTERNAL_H_
 #define BASE_CALLBACK_INTERNAL_H_
 #pragma once
 
 #include <stddef.h>
 
 #include "base/base_export.h"
+#include "base/memory/pass_scoped_ptr.h"
 #include "base/memory/ref_counted.h"
 
 namespace base {
 namespace internal {
 
 // BindStateBase is used to provide an opaque handle that the Callback
 // class can use to represent a function object with bound arguments.  It
 // behaves as an existential type that is used by a corresponding
 // DoInvoke function to perform the function execution.  This allows
 // us to shield the Callback class from the types of the bound argument via
@@ skipping 98 matching lines @@
   typedef const T* StorageType;
 };
 
 // See comment for CallbackParamTraits<T[n]>.
 template <typename T>
 struct CallbackParamTraits<T[]> {
   typedef const T* ForwardType;
   typedef const T* StorageType;
 };
 
+// See comment in PassScopedPtr<> for wanted behavior.
+template <typename T>
+struct CallbackParamTraits<PassScopedPtr<T> > {
+  typedef const PassScopedPtr<T>& ForwardType;
+  typedef subtle::PassScopedPtrAnchor<T> StorageType;
+};
+
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_CALLBACK_INTERNAL_H_