Get rid of virtual Display::CreateScheduler.

components/mus/surfaces/display_compositor.h

Index: components/mus/surfaces/display_compositor.h
diff --git a/components/mus/surfaces/display_compositor.h b/components/mus/surfaces/display_compositor.h
index efbf99236fff5bcd1f7fd297cbfd94474d1996ca..aab8d487ee99546a803d04201b3cfd5012c4bb3d 100644
--- a/components/mus/surfaces/display_compositor.h
+++ b/components/mus/surfaces/display_compositor.h
@@ -16,6 +16,7 @@
 
 namespace cc {
 class Display;
+class SyntheticBeginFrameSource;
 }
 
 namespace mus {
@@ -71,7 +72,10 @@ class DisplayCompositor : public cc::SurfaceFactoryClient,
   cc::SurfaceId surface_id_;
 
   gfx::Size display_size_;
+
+  std::unique_ptr<cc::SyntheticBeginFrameSource> synthetic_begin_frame_source_;
   std::unique_ptr<cc::Display> display_;
+
   DISALLOW_COPY_AND_ASSIGN(DisplayCompositor);
 };