Add a PassScopedPtr into base/memory.

base/callback_internal.h

Index: base/callback_internal.h
diff --git a/base/callback_internal.h b/base/callback_internal.h
index 81c87c0aa749759d9dd987aa16fb0fd3c4e9bdef..28cc2b6fd911806c451c22c5078b8926bd14a291 100644
--- a/base/callback_internal.h
+++ b/base/callback_internal.h
@@ -12,6 +12,7 @@
 #include <stddef.h>
 
 #include "base/base_export.h"
+#include "base/memory/pass_scoped_ptr.h"
 #include "base/memory/ref_counted.h"
 
 namespace base {
@@ -130,6 +131,13 @@ struct CallbackParamTraits<T[]> {
   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