Add Set Authoritative VSync Interval function

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index 249ff7cda34ed7fdafdd904cdf2f64b66498f30e..9e2cbbff2f00db9eba3fcdcae3791d21aa2a556c 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -244,6 +244,14 @@ class COMPOSITOR_EXPORT Compositor
   // Signals swap has aborted (e.g. lost context).
   void OnSwapBuffersAborted();
 
+  // The "authoritative" vsync interval, if provided, will override interval
+  // reported from 3D context. This is typically the value reported by a more
+  // reliable source, e.g, the platform display configuration.
+  // In the particular case of ChromeOS -- this is the value queried through
+  // XRandR, which is more reliable than the value queried through the 3D
+  // context.
+  void SetAuthoritativeVSyncInterval(base::TimeDelta interval) const;
+
   // LayerTreeHostClient implementation.
   void WillBeginMainFrame(int frame_id) override {}
   void DidBeginMainFrame() override {}