[glom] LayoutWidgetMenu: Use std::unique_ptr<> instead of naked new.

[Murray Cumming <murrayc src gnome org>]

commit 89dfe01916c4d71904146e6fdf03103f3154c8e4
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Feb 5 11:06:00 2016 +0100

    LayoutWidgetMenu: Use std::unique_ptr<> instead of naked new.
    
    I am not very happy with passing the raw pointer to gtkmm's
    attach_to_widget(), but that seems to be the normal use of
    unique_ptr<>::operator*() and unique_ptr<>::get(),
    as long as we don't expect the receiving API to take any
    ownership.

 glom/utility_widgets/layoutwidgetmenu.cc |    5 +----
 glom/utility_widgets/layoutwidgetmenu.h  |    2 +-
 2 files changed, 2 insertions(+), 5 deletions(-)
---
diff --git a/glom/utility_widgets/layoutwidgetmenu.cc b/glom/utility_widgets/layoutwidgetmenu.cc
index cc22e34..6322cc6 100644
--- a/glom/utility_widgets/layoutwidgetmenu.cc
+++ b/glom/utility_widgets/layoutwidgetmenu.cc
@@ -29,9 +29,6 @@ namespace Glom
 {
 
 LayoutWidgetMenu::LayoutWidgetMenu()
-#ifndef GLOM_ENABLE_CLIENT_ONLY
-  : m_pMenuPopup(nullptr)
-#endif
 {
   #ifndef GLOM_ENABLE_CLIENT_ONLY
   m_refActionGroup = Gio::SimpleActionGroup::create();
@@ -122,7 +119,7 @@ void LayoutWidgetMenu::setup_menu(Gtk::Widget* widget)
   menu->append(_("Delete"), "context.delete");
 
 
-  m_pMenuPopup = new Gtk::Menu(menu);
+  m_pMenuPopup = std::make_unique<Gtk::Menu>(menu);
   m_pMenuPopup->attach_to_widget(*widget);
 
   if(pApp)
diff --git a/glom/utility_widgets/layoutwidgetmenu.h b/glom/utility_widgets/layoutwidgetmenu.h
index ac28153..d94495d 100644
--- a/glom/utility_widgets/layoutwidgetmenu.h
+++ b/glom/utility_widgets/layoutwidgetmenu.h
@@ -49,7 +49,7 @@ public:
     
 protected:
 #ifndef GLOM_ENABLE_CLIENT_ONLY    
-  Gtk::Menu* m_pMenuPopup;
+  std::unique_ptr<Gtk::Menu> m_pMenuPopup;
 
   //TODO_Performance: //Presumably we waste lots of memory by having this in each layout widget. Maybe we 
can use one shared menu.
   Glib::RefPtr<Gio::SimpleActionGroup> m_refActionGroup;