Move enum MenuAnchorPosition to reduce deps on menu_item_view.h

ui/views/controls/scrollbar/base_scroll_bar.cc

Index: ui/views/controls/scrollbar/base_scroll_bar.cc
diff --git a/ui/views/controls/scrollbar/base_scroll_bar.cc b/ui/views/controls/scrollbar/base_scroll_bar.cc
index 99ec75a5510baa15918982b277ed4243e63e9ca2..5e4d6a56fa384d09ee9687b319bf218a14e3ed17 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.cc
+++ b/ui/views/controls/scrollbar/base_scroll_bar.cc
@@ -305,11 +305,16 @@ void BaseScrollBar::ShowContextMenuForView(View* source,
   menu->AppendSeparator();
   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPrev);
   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollNext);
-  if (menu_runner_->RunMenuAt(GetWidget(), NULL, gfx::Rect(p, gfx::Size()),
-          views::MenuItemView::TOPLEFT, source_type, MenuRunner::HAS_MNEMONICS |
-          views::MenuRunner::CONTEXT_MENU) ==
-      MenuRunner::MENU_DELETED)
+  if (menu_runner_->RunMenuAt(
+          GetWidget(),
+          NULL,
+          gfx::Rect(p, gfx::Size()),
+          MENU_ANCHOR_TOPLEFT,
+          source_type,
+          MenuRunner::HAS_MNEMONICS | views::MenuRunner::CONTEXT_MENU) ==
+      MenuRunner::MENU_DELETED) {
     return;
+  }
 }
 
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