mash: Migrate shelf menus to wm common types

ash/shell/context_menu.h

Index: ash/shell/context_menu.h
diff --git a/ash/shell/context_menu.h b/ash/shell/context_menu.h
index b604884f56d9d845e61e81d2bbbcea7b7c769355..9c59e7e74efea11545c4f6a8888e4d13ecf25b68 100644
--- a/ash/shell/context_menu.h
+++ b/ash/shell/context_menu.h
@@ -11,7 +11,7 @@
 
 namespace ash {
 
-class Shelf;
+class WmShelf;
 
 namespace shell {
 
@@ -19,7 +19,7 @@ namespace shell {
 class ContextMenu : public ui::SimpleMenuModel,
                     public ui::SimpleMenuModel::Delegate {
  public:
-  explicit ContextMenu(Shelf* shelf);
+  explicit ContextMenu(WmShelf* wm_shelf);
   ~ContextMenu() override;
 
   // ui::SimpleMenuModel::Delegate overrides:
@@ -35,7 +35,7 @@ class ContextMenu : public ui::SimpleMenuModel,
     MENU_ALIGNMENT_MENU,
   };
 
-  Shelf* shelf_;
+  WmShelf* wm_shelf_;
   ShelfAlignmentMenu alignment_menu_;
 
   DISALLOW_COPY_AND_ASSIGN(ContextMenu);