Move enum MenuAnchorPosition to reduce deps on menu_item_view.h

ash/shell/window_type_launcher.cc

Index: ash/shell/window_type_launcher.cc
diff --git a/ash/shell/window_type_launcher.cc b/ash/shell/window_type_launcher.cc
index 9352823f457cde91decbe34c6366d0f616e3a5a9..bfd4775da6e7d9307bfc6b9a56f9d7d0d4ab73ec 100644
--- a/ash/shell/window_type_launcher.cc
+++ b/ash/shell/window_type_launcher.cc
@@ -387,13 +387,16 @@ void WindowTypeLauncher::ShowContextMenuForView(
                        MenuItemView::NORMAL);
   // MenuRunner takes ownership of root.
   menu_runner_.reset(new MenuRunner(root));
-  if (menu_runner_->RunMenuAt(GetWidget(), NULL,
-        gfx::Rect(point, gfx::Size()),
-        MenuItemView::TOPLEFT,
-        source_type,
-        MenuRunner::HAS_MNEMONICS | views::MenuRunner::CONTEXT_MENU) ==
-        MenuRunner::MENU_DELETED)
+  if (menu_runner_->RunMenuAt(
+          GetWidget(),
+          NULL,
+          gfx::Rect(point, gfx::Size()),
+          views::MENU_ANCHOR_TOPLEFT,
+          source_type,
+          MenuRunner::HAS_MNEMONICS | views::MenuRunner::CONTEXT_MENU) ==
+      MenuRunner::MENU_DELETED) {
     return;
+  }
 }
 
 }  // namespace shell