Adds BeginFrameControl via DevTools.

ui/views/mus/surface_context_factory.h

Index: ui/views/mus/surface_context_factory.h
diff --git a/ui/views/mus/surface_context_factory.h b/ui/views/mus/surface_context_factory.h
index 8516ebb4925fa786e0f629e8f12f0d17bbc809dc..a1f7ee24330b858fc84aabf3d1f294ed7ab91bfd 100644
--- a/ui/views/mus/surface_context_factory.h
+++ b/ui/views/mus/surface_context_factory.h
@@ -52,6 +52,9 @@ class VIEWS_MUS_EXPORT SurfaceContextFactory : public ui::ContextFactory {
   void SetDisplayVSyncParameters(ui::Compositor* compositor,
                                  base::TimeTicks timebase,
                                  base::TimeDelta interval) override {}
+  void SwapBeginFrameSource(
+      ui::Compositor* compositor,
+      std::unique_ptr<cc::BeginFrameSource>* begin_frame_source) override {}
   void SetOutputIsSecure(ui::Compositor* compositor, bool secure) override {}
   void AddObserver(ui::ContextFactoryObserver* observer) override {}
   void RemoveObserver(ui::ContextFactoryObserver* observer) override {}