mash: Use mojo for ShelfItemDelegate and [app] MenuItem.

ash/shell/window_watcher.cc

Index: ash/shell/window_watcher.cc
diff --git a/ash/shell/window_watcher.cc b/ash/shell/window_watcher.cc
index 23cf1d31968d05e90e54d8f65f939ec4d47a8a02..e70d9631d00c2dc9560ef65745bf0f28480b44f9 100644
--- a/ash/shell/window_watcher.cc
+++ b/ash/shell/window_watcher.cc
@@ -114,9 +114,8 @@ void WindowWatcher::OnWindowAdded(aura::Window* new_window) {
 
   model->Add(item);
 
-  std::unique_ptr<ShelfItemDelegate> delegate(
-      new WindowWatcherShelfItemDelegate(id, this));
-  model->SetShelfItemDelegate(id, std::move(delegate));
+  model->SetShelfItemDelegate(
+      id, base::MakeUnique<WindowWatcherShelfItemDelegate>(id, this));
   new_window->SetProperty(kShelfIDKey, id);
 }