Enable BeginFrame scheduling on aura

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index cf115b0238f0646ec43532acbe032ad775f89e8c..ff20e948341faff974c339403252b919b16da9b3 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -220,6 +220,14 @@ class COMPOSITOR_EXPORT Compositor
   // Gets the visibility of the underlying compositor.
   bool IsVisible();
 
+  // 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(const base::TimeDelta& interval);
+
   // Returns the widget for this compositor.
   gfx::AcceleratedWidget widget() const { return widget_; }