Hook up ui::Compositor to Display's BeginFrameSource

components/mus/surfaces/direct_output_surface.h

Index: components/mus/surfaces/direct_output_surface.h
diff --git a/components/mus/surfaces/direct_output_surface.h b/components/mus/surfaces/direct_output_surface.h
index b32d0cdd85aa3b960e88d1431bd2ad984ad613a7..73c6e8adfb97377ffa61c12fdb73a5279295b125 100644
--- a/components/mus/surfaces/direct_output_surface.h
+++ b/components/mus/surfaces/direct_output_surface.h
@@ -6,22 +6,31 @@
 #define COMPONENTS_MUS_SURFACES_DIRECT_OUTPUT_SURFACE_H_
 
 #include "cc/output/output_surface.h"
+#include "cc/scheduler/begin_frame_source.h"
+#include "components/mus/surfaces/surfaces_context_provider.h"
+#include "components/mus/surfaces/surfaces_context_provider_delegate.h"
 
 namespace mus {
 
 // An OutputSurface implementation that directly draws and
 // swaps to an actual GL surface.
-class DirectOutputSurface : public cc::OutputSurface {
+class DirectOutputSurface : public cc::OutputSurface,
+                            public SurfacesContextProviderDelegate {
  public:
   explicit DirectOutputSurface(
-      const scoped_refptr<cc::ContextProvider>& context_provider);
+      scoped_refptr<SurfacesContextProvider> context_provider,
+      base::SingleThreadTaskRunner* task_runner);
   ~DirectOutputSurface() override;
 
   // cc::OutputSurface implementation
   bool BindToClient(cc::OutputSurfaceClient* client) override;
   void SwapBuffers(cc::CompositorFrame* frame) override;
 
+  // SurfacesContextProviderDelegate implementation
+  void OnVSyncParametersUpdated(int64_t timebase, int64_t interval) override;
+
  private:
+  scoped_ptr<cc::SyntheticBeginFrameSource> synthetic_begin_frame_source_;
   base::WeakPtrFactory<DirectOutputSurface> weak_ptr_factory_;
 };