RenderWidget popup should be a NSWindow so it can go outside the main window.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index d821a8e11b077368e52b7b1f114ad2a87de79721..9a2adbc769a6ef437d55d288693f8a152d2d60b5 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1448,7 +1448,10 @@ void WebContentsImpl::ShowCreatedWidget(int route_id,
   if (is_fullscreen) {
     widget_host_view->InitAsFullscreen(GetRenderWidgetHostView());
   } else {
-    widget_host_view->InitAsPopup(GetRenderWidgetHostView(), initial_pos);
+    WebContentsViewDelegate* delegate =
+        GetContentClient()->browser()->GetWebContentsViewDelegate(this);
+    widget_host_view->InitAsPopup(GetRenderWidgetHostView(),
+                                  initial_pos, delegate);
   }
 
   RenderWidgetHostImpl* render_widget_host_impl =