sky/shell should link with sky/engine

sky/viewer/document_view.cc

Index: sky/viewer/document_view.cc
diff --git a/sky/viewer/document_view.cc b/sky/viewer/document_view.cc
index 09e3a21e458aa3413d3226359af0e6d13e5867e7..1a2e2867f1739ece9e6161c6d0cfa26c3811d0bf 100644
--- a/sky/viewer/document_view.cc
+++ b/sky/viewer/document_view.cc
@@ -279,18 +279,14 @@ void DocumentView::didCreateScriptContext(blink::WebLocalFrame* frame,
                          gin::ConvertToV8(isolate, internals));
 }
 
-blink::ServiceProvider& DocumentView::services() {
-  return *this;
+blink::ServiceProvider* DocumentView::services() {
+  return this;
 }
 
 mojo::NavigatorHost* DocumentView::NavigatorHost() {
   return navigator_host_.get();
 }
 
-mojo::Shell* DocumentView::Shell() {
-  return shell_;
-}
-
 void DocumentView::OnViewBoundsChanged(mojo::View* view,
                                        const mojo::Rect& old_bounds,
                                        const mojo::Rect& new_bounds) {