Move base to DEPS

base/cancelable_callback.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.
-//
-// CancelableCallback is a wrapper around base::Callback that allows
-// cancellation of a callback. CancelableCallback takes a reference on the
-// wrapped callback until this object is destroyed or Reset()/Cancel() are
-// called.
-//
-// NOTE:
-//
-// Calling CancelableCallback::Cancel() brings the object back to its natural,
-// default-constructed state, i.e., CancelableCallback::callback() will return
-// a null callback.
-//
-// THREAD-SAFETY:
-//
-// CancelableCallback objects must be created on, posted to, cancelled on, and
-// destroyed on the same thread.
-//
-//
-// EXAMPLE USAGE:
-//
-// In the following example, the test is verifying that RunIntensiveTest()
-// Quit()s the message loop within 4 seconds. The cancelable callback is posted
-// to the message loop, the intensive test runs, the message loop is run,
-// then the callback is cancelled.
-//
-// void TimeoutCallback(const std::string& timeout_message) {
-//   FAIL() << timeout_message;
-//   MessageLoop::current()->QuitWhenIdle();
-// }
-//
-// CancelableClosure timeout(base::Bind(&TimeoutCallback, "Test timed out."));
-// MessageLoop::current()->PostDelayedTask(FROM_HERE, timeout.callback(),
-//                                         4000)  // 4 seconds to run.
-// RunIntensiveTest();
-// MessageLoop::current()->Run();
-// timeout.Cancel();  // Hopefully this is hit before the timeout callback runs.
-//
-
-#ifndef BASE_CANCELABLE_CALLBACK_H_
-#define BASE_CANCELABLE_CALLBACK_H_
-
-#include "base/base_export.h"
-#include "base/bind.h"
-#include "base/callback.h"
-#include "base/callback_internal.h"
-#include "base/compiler_specific.h"
-#include "base/logging.h"
-#include "base/memory/weak_ptr.h"
-
-namespace base {
-
-template <typename Sig>
-class CancelableCallback;
-
-template <typename... A>
-class CancelableCallback<void(A...)> {
- public:
-  CancelableCallback() : weak_factory_(this) {}
-
-  // |callback| must not be null.
-  explicit CancelableCallback(const base::Callback<void(A...)>& callback)
-      : callback_(callback), weak_factory_(this) {
-    DCHECK(!callback.is_null());
-    InitializeForwarder();
-  }
-
-  ~CancelableCallback() {}
-
-  // Cancels and drops the reference to the wrapped callback.
-  void Cancel() {
-    weak_factory_.InvalidateWeakPtrs();
-    forwarder_.Reset();
-    callback_.Reset();
-  }
-
-  // Returns true if the wrapped callback has been cancelled.
-  bool IsCancelled() const {
-    return callback_.is_null();
-  }
-
-  // Sets |callback| as the closure that may be cancelled. |callback| may not
-  // be null. Outstanding and any previously wrapped callbacks are cancelled.
-  void Reset(const base::Callback<void(A...)>& callback) {
-    DCHECK(!callback.is_null());
-
-    // Outstanding tasks (e.g., posted to a message loop) must not be called.
-    Cancel();
-
-    // |forwarder_| is no longer valid after Cancel(), so re-bind.
-    InitializeForwarder();
-
-    callback_ = callback;
-  }
-
-  // Returns a callback that can be disabled by calling Cancel().
-  const base::Callback<void(A...)>& callback() const {
-    return forwarder_;
-  }
-
- private:
-  void Forward(A... args) const {
-    callback_.Run(args...);
-  }
-
-  // Helper method to bind |forwarder_| using a weak pointer from
-  // |weak_factory_|.
-  void InitializeForwarder() {
-    forwarder_ = base::Bind(&CancelableCallback<void(A...)>::Forward,
-                            weak_factory_.GetWeakPtr());
-  }
-
-  // The wrapper closure.
-  base::Callback<void(A...)> forwarder_;
-
-  // The stored closure that may be cancelled.
-  base::Callback<void(A...)> callback_;
-
-  // Used to ensure Forward() is not run when this object is destroyed.
-  base::WeakPtrFactory<CancelableCallback<void(A...)>> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(CancelableCallback);
-};
-
-typedef CancelableCallback<void(void)> CancelableClosure;
-
-}  // namespace base
-
-#endif  // BASE_CANCELABLE_CALLBACK_H_