Read compositor VSync information from platform, when possible

ui/compositor/compositor_observer.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.
 
 #ifndef UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_
 #define UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_
 
 #include "base/time/time.h"
 #include "ui/compositor/compositor_export.h"
 
@@ skipping 20 matching lines @@
 
   // Called when compositing completes: the present to screen has completed.
   virtual void OnCompositingEnded(Compositor* compositor) = 0;
 
   // Called when compositing is aborted (e.g. lost graphics context).
   virtual void OnCompositingAborted(Compositor* compositor) = 0;
 
   // 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() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_