Add GetSurfaceManager to ui::ContextFactory.

ui/views/mus/surface_context_factory.cc

Index: ui/views/mus/surface_context_factory.cc
diff --git a/ui/views/mus/surface_context_factory.cc b/ui/views/mus/surface_context_factory.cc
index b62a656536c2ddf3051c07a4ab4d97a612e7e2a8..1d643095e830cad370ab2c51a11f911facd50f96 100644
--- a/ui/views/mus/surface_context_factory.cc
+++ b/ui/views/mus/surface_context_factory.cc
@@ -93,6 +93,11 @@ SurfaceContextFactory::CreateSurfaceIdAllocator() {
       new cc::SurfaceIdAllocator(next_surface_id_namespace_++));
 }
 
+cc::SurfaceManager* SurfaceContextFactory::GetSurfaceManager() {
+  // NOTIMPLEMENTED();
+  return nullptr;
+}
+
 void SurfaceContextFactory::ResizeDisplay(ui::Compositor* compositor,
                                           const gfx::Size& size) {
   // NOTIMPLEMENTED();