Use DwmGetCompositionTimingInfo to get vsync info on Windows

BUG=


Review URL: https://chromiumcodereview.appspot.com/10825053

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150395 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 0 deletions

diff --git a/ui/surface/accelerated_surface_win.h b/ui/surface/accelerated_surface_win.h
index ca46523..b904e4f 100644
--- a/ui/surface/accelerated_surface_win.h
+++ b/ui/surface/accelerated_surface_win.h
@@ -77,6 +77,18 @@ 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. i.e.:
+  // inteval_in_seconds = interval_numerator / interval_denominator;
+  // For example, some machines will return an interval_numerator of 1001
+  // and an interval_denominator of 60000, resulting in an interval of
+  // 1001/60000 ~= .016683 seconds
+  // Note: This function assumes lock_ is acquired.
+  void GetPresentationStats(base::TimeTicks* timebase,
+                            uint32* interval_numerator,
+                            uint32* interval_denominator);
+
   // The thread with which this presenter has affinity.
   PresentThread* const present_thread_;