Convert WaitableEvent::EventCallback to OnceCallback

base/synchronization/waitable_event_watcher.h

 // 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.
 
 #ifndef BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_
 #define BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_
 
 #include "base/base_export.h"
 #include "base/macros.h"
 #include "base/sequence_checker.h"
@@ skipping 17 matching lines @@
 // Each instance of this object can be waiting on a single WaitableEvent. When
 // the waitable event is signaled, a callback is invoked on the sequence that
 // called StartWatching(). This callback can be deleted by deleting the waiter.
 //
 // Typical usage:
 //
 //   class MyClass {
 //    public:
 //     void DoStuffWhenSignaled(WaitableEvent *waitable_event) {
 //       watcher_.StartWatching(waitable_event,
-//           base::Bind(&MyClass::OnWaitableEventSignaled, this);
+//           base::BindOnce(&MyClass::OnWaitableEventSignaled, this);
 //     }
 //    private:
 //     void OnWaitableEventSignaled(WaitableEvent* waitable_event) {
 //       // OK, time to do stuff!
 //     }
 //     base::WaitableEventWatcher watcher_;
 //   };
 //
 // In the above example, MyClass wants to "do stuff" when waitable_event
 // becomes signaled. WaitableEventWatcher makes this task easy. When MyClass
 // goes out of scope, the watcher_ will be destroyed, and there is no need to
 // worry about OnWaitableEventSignaled being called on a deleted MyClass
 // pointer.
 //
 // BEWARE: With automatically reset WaitableEvents, a signal may be lost if it
 // occurs just before a WaitableEventWatcher is deleted. There is currently no
 // safe way to stop watching an automatic reset WaitableEvent without possibly
 // missing a signal.
 //
 // NOTE: you /are/ allowed to delete the WaitableEvent while still waiting on
 // it with a Watcher. It will act as if the event was never signaled.
 
 class BASE_EXPORT WaitableEventWatcher
 #if defined(OS_WIN)
     : public win::ObjectWatcher::Delegate
 #endif
 {
  public:
-  typedef Callback<void(WaitableEvent*)> EventCallback;
+  using EventCallback = OnceCallback<void(WaitableEvent*)>;
   WaitableEventWatcher();
 
 #if defined(OS_WIN)
   ~WaitableEventWatcher() override;
 #else
   ~WaitableEventWatcher();
 #endif
 
   // When |event| is signaled, |callback| is called on the sequence that called
   // StartWatching().
-  bool StartWatching(WaitableEvent* event, const EventCallback& callback);
+  bool StartWatching(WaitableEvent* event, EventCallback callback);
 
   // Cancel the current watch. Must be called from the same sequence which
   // started the watch.
   //
   // Does nothing if no event is being watched, nor if the watch has completed.
   // The callback will *not* be called for the current watch after this
   // function returns. Since the callback runs on the same sequence as this
   // function, it cannot be called during this function either.
   void StopWatching();
 
@@ skipping 19 matching lines @@
   // sequence.
   SequenceChecker sequence_checker_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(WaitableEventWatcher);
 };
 
 }  // namespace base
 
 #endif  // BASE_SYNCHRONIZATION_WAITABLE_EVENT_WATCHER_H_