Move enum MenuAnchorPosition to reduce deps on menu_item_view.h

ui/views/controls/menu/menu_delegate.cc

Index: ui/views/controls/menu/menu_delegate.cc
diff --git a/ui/views/controls/menu/menu_delegate.cc b/ui/views/controls/menu/menu_delegate.cc
index 699377f6da224720657e0ca593efdc0a6f921ea0..346902371a6aea17ef0c069e2af3084fd9d0b582 100644
--- a/ui/views/controls/menu/menu_delegate.cc
+++ b/ui/views/controls/menu/menu_delegate.cc
@@ -2,9 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ui/views/controls/menu/menu_config.h"
 #include "ui/views/controls/menu/menu_delegate.h"
 
+#include "ui/events/event.h"
+#include "ui/views/controls/menu/menu_config.h"
+
 namespace views {
 
 MenuDelegate::~MenuDelegate() {}
@@ -131,7 +133,7 @@ int MenuDelegate::GetDragOperations(MenuItemView* sender) {
 
 MenuItemView* MenuDelegate::GetSiblingMenu(MenuItemView* menu,
                                            const gfx::Point& screen_point,
-                                           MenuItemView::AnchorPosition* anchor,
+                                           MenuAnchorPosition* anchor,
                                            bool* has_mnemonics,
                                            MenuButton** button) {
   return NULL;