Callback API Change: Reimplement Bind(); support IgnoreResult, full currying, and use less types

base/template_util.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_TEMPLATE_UTIL_H_
 #define BASE_TEMPLATE_UTIL_H_
 #pragma once
 
 #include <cstddef>  // For size_t.
 
@@ skipping 52 matching lines @@
 // _Modern C++ Design_ for more details on this sort of trick.
 
 struct ConvertHelper {
   template <typename To>
   static YesType Test(To);
 
   template <typename To>
   static NoType Test(...);
 
   template <typename From>
-  static From Create();
+  static From& Create();
 };
 
 // Used to determine if a type is a struct/union/class. Inspired by Boost's
 // is_class type_trait implementation.
 struct IsClassHelper {
   template <typename C>
   static YesType Test(void(C::*)(void));
 
   template <typename C>
   static NoType Test(...);
@@ skipping 16 matching lines @@
 template <typename T>
 struct is_class
     : integral_constant<bool,
                         sizeof(internal::IsClassHelper::Test<T>(0)) ==
                             sizeof(internal::YesType)> {
 };
 
 }  // namespace base
 
 #endif  // BASE_TEMPLATE_UTIL_H_