Use DwmGetCompositionTimingInfo to get vsync info on Windows

ui/surface/accelerated_surface_win.h

Index: ui/surface/accelerated_surface_win.h
diff --git a/ui/surface/accelerated_surface_win.h b/ui/surface/accelerated_surface_win.h
index 2abf0cedc8502d133663054de56b10eccf82f79f..527afdd2c29afeee169a6af5b6f695bb17c38e76 100644
--- a/ui/surface/accelerated_surface_win.h
+++ b/ui/surface/accelerated_surface_win.h
@@ -71,6 +71,13 @@ class SURFACE_EXPORT AcceleratedPresenter
   bool DoRealPresent(HDC dc);
   void DoReleaseSurface();
 
+  // This gets the timestamp and period of the display's last vsync.
+  // The period is represented as a ratio which, when divided, will give you
+  // the interval in seconds.
+  void GetPresentationStats(base::TimeTicks *timebase,

[jbates, 2012/07/30 18:37:51]

- comments should explicitly say how to calculate the frame interval and give
example values, because it's actually the opposite of what is expected. eg:
interval_in_seconds = interval_denominator/interval_numerator
example values: denominator = 1001, numerator = 60000.
- pointer style is typically TimeTicks* timebase in chromium.

[jbates, 2012/07/30 19:27:00]

Err, except in reverse since you already swap them :)

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

Yeah, I just swapped them in a recent commit.  Will update comments.

+                            uint32 *interval_numerator,
+                            uint32 *interval_denominator);
+
   // The thread with which this presenter has affinity.
   PresentThread* const present_thread_;