| // 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_CALLBACK_FORWARD_H_ | 
 | #define BASE_CALLBACK_FORWARD_H_ | 
 |  | 
 | namespace base { | 
 | namespace internal { | 
 |  | 
 | // CopyMode is used to control the copyablity of a Callback. | 
 | // MoveOnly indicates the Callback is not copyable but movable, and Copyable | 
 | // indicates it is copyable and movable. | 
 | enum class CopyMode { | 
 |   MoveOnly, Copyable, | 
 | }; | 
 |  | 
 | }  // namespace internal | 
 |  | 
 | template <typename Signature, | 
 |           internal::CopyMode copy_mode = internal::CopyMode::Copyable> | 
 | class Callback; | 
 |  | 
 | // Syntactic sugar to make Callback<void()> easier to declare since it | 
 | // will be used in a lot of APIs with delayed execution. | 
 | using Closure = Callback<void()>; | 
 |  | 
 | }  // namespace base | 
 |  | 
 | #endif  // BASE_CALLBACK_FORWARD_H_ |