Convert WaitableEvent::EventCallback to OnceCallback

base/message_loop/message_pump_libevent_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "base/message_loop/message_pump_libevent.h"
 
 #include <unistd.h>
 
 #include <memory>
+#include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/waitable_event.h"
@@ skipping 229 matching lines @@
   WaitableEvent event(WaitableEvent::ResetPolicy::AUTOMATIC,
                       WaitableEvent::InitialState::NOT_SIGNALED);
   std::unique_ptr<WaitableEventWatcher> watcher(new WaitableEventWatcher);
 
   // Tell the pump to watch the pipe.
   pump->WatchFileDescriptor(pipefds_[0], false, MessagePumpLibevent::WATCH_READ,
                             &controller, &delegate);
 
   // Make the IO thread wait for |event| before writing to pipefds[1].
   const char buf = 0;
-  const WaitableEventWatcher::EventCallback write_fd_task =
-      Bind(&WriteFDWrapper, pipefds_[1], &buf, 1);
+  WaitableEventWatcher::EventCallback write_fd_task =
+      BindOnce(&WriteFDWrapper, pipefds_[1], &buf, 1);
   io_loop()->task_runner()->PostTask(
-      FROM_HERE, BindOnce(IgnoreResult(&WaitableEventWatcher::StartWatching),
-                          Unretained(watcher.get()), &event, write_fd_task));
+      FROM_HERE,
+      BindOnce(IgnoreResult(&WaitableEventWatcher::StartWatching),
+               Unretained(watcher.get()), &event, std::move(write_fd_task)));
 
   // Queue |event| to signal on |loop|.
   loop.task_runner()->PostTask(
       FROM_HERE, BindOnce(&WaitableEvent::Signal, Unretained(&event)));
 
   // Now run the MessageLoop.
   run_loop.Run();
 
   // StartWatching can move |watcher| to IO thread. Release on IO thread.
   io_loop()->task_runner()->PostTask(
       FROM_HERE,
       BindOnce(&WaitableEventWatcher::StopWatching, Owned(watcher.release())));
 }
 
 }  // namespace
 
 }  // namespace base