Revert of C++ readability review

components/timers/alarm_timer_chromeos.h

-// Copyright 2014 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 COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_
-#define COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
-#include "base/time/time.h"
-#include "base/timer/timer.h"
-
-namespace base {
-class MessageLoop;
-struct PendingTask;
-}
-
-namespace timers {
-// The class implements a timer that is capable of waking the system up from a
-// suspended state.  For example, this is useful for running tasks that are
-// needed for maintaining network connectivity, like sending heartbeat messages.
-// Currently, this feature is only available on Chrome OS systems running linux
-// version 3.11 or higher.  On all other platforms, the AlarmTimer behaves
-// exactly the same way as a regular Timer.
-class AlarmTimer : public base::Timer {
- public:
-  ~AlarmTimer() override;
-
-  bool can_wake_from_suspend() const { return can_wake_from_suspend_; }
-
-  // Sets a hook that will be called when the timer fires and a task has been
-  // queued on |origin_message_loop_|.  Used by tests to wait until a task is
-  // pending in the MessageLoop.
-  void SetTimerFiredCallbackForTest(base::Closure test_callback);
-
-  // Timer overrides.
-  void Stop() override;
-  void Reset() override;
-
- protected:
-  // The constructors for this class are protected because consumers should
-  // instantiate one of the specialized sub-classes defined below instead.
-  AlarmTimer(bool retain_user_task, bool is_repeating);
-  AlarmTimer(const tracked_objects::Location& posted_from,
-             base::TimeDelta delay,
-             const base::Closure& user_task,
-             bool is_repeating);
-
- private:
-  // Common initialization that must be performed by both constructors.  This
-  // really should live in a delegated constructor but the way base::Timer's
-  // constructors are written makes it really hard to do so.
-  void Init();
-
-  // Will be called by the delegate to indicate that the timer has fired and
-  // that the user task should be run.
-  void OnTimerFired();
-
-  // Called when |origin_message_loop_| will be destroyed.
-  void WillDestroyCurrentMessageLoop();
-
-  // Delegate that will manage actually setting the timer.
-  class Delegate;
-  scoped_refptr<Delegate> delegate_;
-
-  // Keeps track of the user task we want to run.  A new one is constructed
-  // every time Reset() is called.
-  scoped_ptr<base::PendingTask> pending_task_;
-
-  // Tracks whether the timer has the ability to wake the system up from
-  // suspend.  This is a runtime check because we won't know if the system
-  // supports being woken up from suspend until the delegate actually tries to
-  // set it up.
-  bool can_wake_from_suspend_;
-
-  // Pointer to the message loop that started the timer.  Used to track the
-  // destruction of that message loop.
-  base::MessageLoop* origin_message_loop_;
-
-  // Observes |origin_message_loop_| and informs this class if it will be
-  // destroyed.
-  class MessageLoopObserver;
-  scoped_ptr<MessageLoopObserver> message_loop_observer_;
-
-  base::WeakPtrFactory<AlarmTimer> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(AlarmTimer);
-};
-
-// As its name suggests, a OneShotAlarmTimer runs a given task once.  It does
-// not remember the task that was given to it after it has fired and does not
-// repeat.  Useful for fire-and-forget tasks.
-class OneShotAlarmTimer : public AlarmTimer {
- public:
-  // Constructs a basic OneShotAlarmTimer.  An AlarmTimer constructed this way
-  // requires that Start() is called before Reset() is called.
-  OneShotAlarmTimer();
-  ~OneShotAlarmTimer() override;
-};
-
-// A RepeatingAlarmTimer takes a task and delay and repeatedly runs the task
-// using the specified delay as an interval between the runs until it is
-// explicitly stopped.  It remembers both the task and the delay it was given
-// after it fires.
-class RepeatingAlarmTimer : public AlarmTimer {
- public:
-  // Constructs a basic RepeatingAlarmTimer.  An AlarmTimer constructed this way
-  // requires that Start() is called before Reset() is called.
-  RepeatingAlarmTimer();
-
-  // Constructs a RepeatingAlarmTimer with pre-populated parameters but does not
-  // start it.  Useful if |user_task| or |delay| are not going to change.
-  // Reset() can be called immediately after constructing an AlarmTimer in this
-  // way.
-  RepeatingAlarmTimer(const tracked_objects::Location& posted_from,
-                      base::TimeDelta delay,
-                      const base::Closure& user_task);
-
-  ~RepeatingAlarmTimer() override;
-};
-
-// A SimpleAlarmTimer only fires once but remembers the task that it was given
-// even after it has fired.  Useful if you want to run the same task multiple
-// times but not at a regular interval.
-class SimpleAlarmTimer : public AlarmTimer {
- public:
-  // Constructs a basic SimpleAlarmTimer.  An AlarmTimer constructed this way
-  // requires that Start() is called before Reset() is called.
-  SimpleAlarmTimer();
-
-  // Constructs a SimpleAlarmTimer with pre-populated parameters but does not
-  // start it.  Useful if |user_task| or |delay| are not going to change.
-  // Reset() can be called immediately after constructing an AlarmTimer in this
-  // way.
-  SimpleAlarmTimer(const tracked_objects::Location& posted_from,
-                   base::TimeDelta delay,
-                   const base::Closure& user_task);
-
-  ~SimpleAlarmTimer() override;
-};
-
-}  // namespace timers
-
-#endif  // COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_