Add a comment to caution that timer::stop() should not be called too much

third_party/WebKit/Source/platform/Timer.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 40 matching lines @@
 
     void startRepeating(double repeatInterval, const WebTraceLocation& caller)
     {
         start(repeatInterval, repeatInterval, caller);
     }
     void startOneShot(double interval, const WebTraceLocation& caller)
     {
         start(interval, 0, caller);
     }
 
+    // Timer cancellation is supported but not free. Please be careful not to
+    // cause a flood of timer cancellations.
     void stop();
     bool isActive() const;
     const WebTraceLocation& location() const { return m_location; }
 
     double nextFireInterval() const;
     double repeatInterval() const { return m_repeatInterval; }
 
     void augmentRepeatInterval(double delta) {
         double now = timerMonotonicallyIncreasingTime();
         setNextFireTime(now, std::max(m_nextFireTime - now + delta, 0.0));
@@ skipping 153 matching lines @@
 NO_LAZY_SWEEP_SANITIZE_ADDRESS
 inline bool TimerBase::isActive() const
 {
     ASSERT(m_thread == currentThread());
     return m_cancellableTimerTask;
 }
 
 } // namespace blink
 
 #endif // Timer_h