mash: Convert AshPopupAlignmentDelegate to wm common types

ash/shelf/shelf.cc

Index: ash/shelf/shelf.cc
diff --git a/ash/shelf/shelf.cc b/ash/shelf/shelf.cc
index cbc1e15c4b9f37fb03aeeacba823d785f5afedbb..e687287f6f8c8ec6d297406fcc841fabe32f8b71 100644
--- a/ash/shelf/shelf.cc
+++ b/ash/shelf/shelf.cc
@@ -73,18 +73,6 @@ Shelf* Shelf::ForWindow(const aura::Window* window) {
   return shelf_widget ? shelf_widget->shelf() : nullptr;
 }
 
-// static
-Shelf* Shelf::ForDisplayId(int64_t display_id) {
-  for (aura::Window* window : Shell::GetInstance()->GetAllRootWindows()) {
-    RootWindowSettings* settings = GetRootWindowSettings(window);
-    if (settings->display_id == display_id && settings->controller) {
-      ShelfWidget* shelf_widget = settings->controller->shelf_widget();
-      return shelf_widget ? shelf_widget->shelf() : nullptr;
-    }
-  }
-  return nullptr;
-}
-
 void Shelf::SetAlignment(ShelfAlignment alignment) {
   if (alignment_ == alignment)
     return;