Use DwmGetCompositionTimingInfo to get vsync info on Windows

base/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 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 46 matching lines @@
   TimeDelta() : delta_(0) {
   }
 
   // Converts units of time to TimeDeltas.
   static TimeDelta FromDays(int64 days);
   static TimeDelta FromHours(int64 hours);
   static TimeDelta FromMinutes(int64 minutes);
   static TimeDelta FromSeconds(int64 secs);
   static TimeDelta FromMilliseconds(int64 ms);
   static TimeDelta FromMicroseconds(int64 us);
+#if defined(OS_WIN)
+  static TimeDelta FromQPCValue(LONGLONG qpcValue);

[brianderson, 2012/07/30 19:38:13]

jar, is it ok that we add functions to convert native qpc values to TimeDeltas
and TimeTicks?  We are receiving qpc values from a windows API call and need
this functionality.

[apatrick_chromium, 2012/07/30 19:43:31]

Google style is qpc_value.

+#endif
 
   // Converts an integer value representing TimeDelta to a class. This is used
   // when deserializing a |TimeDelta| structure, using a value known to be
   // compatible. It is not provided as a constructor because the integer type
   // may be unclear from the perspective of a caller.
   static TimeDelta FromInternalValue(int64 delta) {
     return TimeDelta(delta);
   }
 
   // Returns the internal numeric value of the TimeDelta object. Please don't
@@ skipping 426 matching lines @@
   // high-res time (i.e. HighResNow()). On systems where a global trace clock
   // is defined, timestamping TraceEvents's with this value guarantees
   // synchronization between events collected inside chrome and events
   // collected outside (e.g. kernel, X server).
   static TimeTicks NowFromSystemTraceTime();
 
 #if defined(OS_WIN)
   // Get the absolute value of QPC time drift. For testing.
   static int64 GetQPCDriftMicroseconds();
 
+  static TimeTicks FromQPCValue(LONGLONG qpcValue);

[apatrick_chromium, 2012/07/30 19:43:31]

Same here.

+
   // Returns true if the high resolution clock is working on this system.
   // This is only for testing.
   static bool IsHighResClockWorking();
 #endif
 
   // Returns true if this object has not been initialized.
   bool is_null() const {
     return ticks_ == 0;
   }
 
@@ skipping 76 matching lines @@
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
 }  // namespace base
 
 #endif  // BASE_TIME_H_