|  | // 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_ |