Implement Time::ThreadNow() on Mac.

base/time/time.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.
 
 // Time represents an absolute point in time, internally represented as
 // microseconds (s/1,000,000) since the Windows epoch (1601-01-01 00:00:00 UTC)
 // (See http://crbug.com/14734).  System-dependent clock interface routines are
 // defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 530 matching lines @@
   // Returns a platform-dependent high-resolution tick count. Implementation
   // is hardware dependent and may or may not return sub-millisecond
   // resolution.  THIS CALL IS GENERALLY MUCH MORE EXPENSIVE THAN Now() AND
   // SHOULD ONLY BE USED WHEN IT IS REALLY NEEDED.
   static TimeTicks HighResNow();
 
   static bool IsHighResNowFastAndReliable();
 
   // Returns true if ThreadNow() is supported on this system.
   static bool IsThreadNowSupported() {
-#if defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)
+#if (defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)) || \
+    (defined(OS_MACOSX) && !defined(OS_IOS))
     return true;
 #else
     return false;
 #endif
   }
 
   // Returns thread-specific CPU-time on systems that support this feature.
   // Needs to be guarded with a call to IsThreadNowSupported(). Use this timer
   // to (approximately) measure how much time the calling thread spent doing
   // actual work vs. being de-scheduled. May return bogus results if the thread
@@ skipping 121 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_TIME_H_