Read compositor VSync information from platform, when possible

ui/compositor/compositor_observer.h

Index: ui/compositor/compositor_observer.h
diff --git a/ui/compositor/compositor_observer.h b/ui/compositor/compositor_observer.h
index aced251b3f99d9410c15a714c8b5b1e110fe16b7..badc5b466c93e0dcbc8eafd5c0ac9107e27d3fb8 100644
--- a/ui/compositor/compositor_observer.h
+++ b/ui/compositor/compositor_observer.h
@@ -38,11 +38,6 @@ class COMPOSITOR_EXPORT CompositorObserver {
   // Called when the compositor lock state changes.
   virtual void OnCompositingLockStateChanged(Compositor* compositor) = 0;
 
-  // Called when the compositor has received updated VSync parameters.
-  virtual void OnUpdateVSyncParameters(Compositor* compositor,
-                                       base::TimeTicks timebase,
-                                       base::TimeDelta interval) = 0;
-
  protected:
   virtual ~CompositorObserver() {}
 };