Multi-select <select> in 'external popup window'

content/browser/web_contents/web_contents_view_win.cc

Index: content/browser/web_contents/web_contents_view_win.cc
diff --git a/content/browser/web_contents/web_contents_view_win.cc b/content/browser/web_contents/web_contents_view_win.cc
index b24079e006fcf1fb988767e500cffadb7455fb9e..92eff7ed6dc37b91808fb840a44f4e67b2310d5e 100644
--- a/content/browser/web_contents/web_contents_view_win.cc
+++ b/content/browser/web_contents/web_contents_view_win.cc
@@ -245,6 +245,17 @@ void WebContentsViewWin::ShowContextMenu(
     delegate_->ShowContextMenu(params);
 }
 
+void WebContentsViewWin::ShowPopupMenu(const gfx::Rect& bounds,
+                                       int item_height,
+                                       double item_font_size,
+                                       int selected_item,
+                                       const std::vector<WebMenuItem>& items,
+                                       bool right_aligned,
+                                       bool allow_multiple_selection) {
+  // External popup menus are only used on Mac and Android.
+  NOTIMPLEMENTED();
+}
+
 void WebContentsViewWin::StartDragging(const WebDropData& drop_data,
                                        WebKit::WebDragOperationsMask operations,
                                        const SkBitmap& image,