time: Add a static TimeTicks method that returns the underlying clock

base/time/time_mac.cc

 // 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.
 
 #include "base/time/time.h"
 
 #include <CoreFoundation/CFDate.h>
 #include <CoreFoundation/CFTimeZone.h>
 #include <mach/mach.h>
 #include <mach/mach_time.h>
@@ skipping 219 matching lines @@
 TimeTicks TimeTicks::Now() {
   return TimeTicks(ComputeCurrentTicks());
 }
 
 // static
 bool TimeTicks::IsHighResolution() {
   return true;
 }
 
 // static
+TimeTicks::Clock TimeTicks::GetClock() {
+#if defined(OS_IOS)
+  return Clock::IOS_CF_ABSOLUTE_TIME_MINUS_KERN_BOOTTIME;
+#else
+  return Clock::MAC_MACH_ABSOLUTE_TIME;
+#endif  // defined(OS_IOS)
+}
+
+// static
 ThreadTicks ThreadTicks::Now() {
   return ThreadTicks(ComputeThreadTicks());
 }
 
 }  // namespace base