text: // Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2012
  // Google Inc. All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //    * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //    * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //    * Neither the name of Google Inc. nor the name Chromium Embedded
  // Framework nor the names of its contributors may be used to endorse
  // or promote products derived from this software without specific prior
  // written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // This defines helpful methods for dealing with Callbacks.  Because Callbacks
  // are implemented using templates, with a class per callback signature, adding
  // methods to Callback<> itself is unattractive (lots of extra code gets
  // generated).  Instead, consider adding methods here.
  //
  // ResetAndReturn(&cb) is like cb.Reset() but allows executing a callback (via a
  // copy) after the original callback is Reset().  This can be handy if Run()
  // reads/writes the variable holding the Callback.
  
  #ifndef CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
  #define CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
  #pragma once
  
  #if defined(BASE_CALLBACK_HELPERS_H_)
  // Do nothing if the Chromium header has already been included.
  // This can happen in cases where Chromium code is used directly by the
  // client application. When using Chromium code directly always include
  // the Chromium header first to avoid type conflicts.
  #elif defined(USING_CHROMIUM_INCLUDES)
  // When building CEF include the Chromium header directly.
  #include "base/callback_helpers.h"
  #else  // !USING_CHROMIUM_INCLUDES
  // The following is substantially similar to the Chromium implementation.
  // If the Chromium implementation diverges the below implementation should be
  // updated to match.
  
  #include "include/base/cef_basictypes.h"
  #include "include/base/cef_build.h"
  #include "include/base/cef_callback.h"
  #include "include/base/cef_macros.h"
  
  namespace base {
  
  template <typename Sig>
  base::Callback<Sig> ResetAndReturn(base::Callback<Sig>* cb) {
    base::Callback<Sig> ret(*cb);
    cb->Reset();
    return ret;
  }
  
  // ScopedClosureRunner is akin to scoped_ptr for Closures. It ensures that the
  // Closure is executed and deleted no matter how the current scope exits.
  class ScopedClosureRunner {
   public:
    ScopedClosureRunner();
    explicit ScopedClosureRunner(const Closure& closure);
    ~ScopedClosureRunner();
  
    void Reset();
    void Reset(const Closure& closure);
    Closure Release() WARN_UNUSED_RESULT;
  
   private:
    Closure closure_;
  
    DISALLOW_COPY_AND_ASSIGN(ScopedClosureRunner);
  };
  
  }  // namespace base
  
  #endif  // !USING_CHROMIUM_INCLUDES
  
  #endif  // CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
  