Fix regression where high resolution timers could be activated even under...

base/time.h

 // Copyright (c) 2010 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.
 
 // Time represents an absolute point in time, internally represented as
 // microseconds (s/1,000,000) since a platform-dependent epoch.  Each
 // platform's epoch, along with other system-dependent clock interface
 // routines, is defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 265 matching lines @@
   // When disabling the high resolution timer, this function will not cause
   // the high resolution timer to be deactivated, but will prevent future
   // activations.
   // Must be called from the main thread.
   // For more details see comments in time_win.cc.
   static void EnableHighResolutionTimer(bool enable);
 
   // Activates or deactivates the high resolution timer based on the |activate|
   // flag.  If the HighResolutionTimer is not Enabled (see
   // EnableHighResolutionTimer), this function will return false.  Otherwise
-  // returns true.
+  // returns true.  Each successful activate call must be paired with a
+  // subsequent deactivate call.
   // All callers to activate the high resolution timer must eventually call
   // this function to deactivate the high resolution timer.
   static bool ActivateHighResolutionTimer(bool activate);
+
+  // Returns true if the high resolution timer is both enabled and activated.
+  // This is provided for testing only, and is not tracked in a thread-safe
+  // way.
+  static bool IsHighResolutionTimerInUse();
 #endif
 
   // Converts an exploded structure representing either the local time or UTC
   // into a Time class.
   static Time FromUTCExploded(const Exploded& exploded) {
     return FromExploded(false, exploded);
   }
   static Time FromLocalExploded(const Exploded& exploded) {
     return FromExploded(true, exploded);
   }
@@ skipping 98 matching lines @@
 
   // The representation of Jan 1, 1970 UTC in microseconds since the
   // platform-dependent epoch.
   static const int64 kTimeTToMicrosecondsOffset;
 
 #if defined(OS_WIN)
   // Indicates whether fast timers are usable right now.  For instance,
   // when using battery power, we might elect to prevent high speed timers
   // which would draw more power.
   static bool high_resolution_timer_enabled_;
+  // Count of activations on the high resolution timer.  Not tracked
+  // in a thread safe way.

[jar (doing other things), 2010/10/20 00:37:19]

Please add to comment:
...and used ONLY by tests which are running single threaded.

+  static int high_resolution_timer_activated_;
 #endif
 
   // Time in microseconds in UTC.
   int64 us_;
 };
 
 inline Time TimeDelta::operator+(Time t) const {
   return Time(t.us_ + delta_);
 }
 
@@ skipping 132 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_H_