DetachFromSequence in Timer::Stop()

base/timer/timer.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.
 
 // OneShotTimer and RepeatingTimer provide a simple timer API.  As the names
 // suggest, OneShotTimer calls you back once after a time delay expires.
 // RepeatingTimer on the other hand calls you back periodically with the
 // prescribed time interval.
 //
 // OneShotTimer and RepeatingTimer both cancel the timer when they go out of
@@ skipping 185 matching lines @@
   // The desired run time of |user_task_|. The user may update this at any time,
   // even if their previous request has not run yet. If |desired_run_time_| is
   // greater than |scheduled_run_time_|, a continuation task will be posted to
   // wait for the remaining time. This allows us to reuse the pending task so as
   // not to flood the delayed queues with orphaned tasks when the user code
   // excessively Stops and Starts the timer. This time can be a "zero" TimeTicks
   // if the task must be run immediately.
   TimeTicks desired_run_time_;
 
   // Timer isn't thread-safe and must only be used on its origin sequence
-  // (sequence on which it was started).
+  // (sequence on which it was started). Once fully Stop()'ed it may be
+  // destroyed or restarted on another sequence.
   SequenceChecker origin_sequence_checker_;
 
   // Repeating timers automatically post the task again before calling the task
   // callback.
   const bool is_repeating_;
 
   // If true, hold on to the |user_task_| closure object for reuse.
   const bool retain_user_task_;
 
   // The tick clock used to calculate the run time for scheduled tasks.
@@ skipping 91 matching lines @@
 // to link in MSVC. But clang-plugin does not allow inline definitions of
 // virtual methods, so the inline definition lives in the header file here
 // to satisfy both.
 inline void DelayTimer::Reset() {
   Timer::Reset();
 }
 
 }  // namespace base
 
 #endif  // BASE_TIMER_TIMER_H_