Align the base of the shelf's context menu to the top edge of the shelf.

ui/views/controls/menu/menu_runner.h

Index: ui/views/controls/menu/menu_runner.h
diff --git a/ui/views/controls/menu/menu_runner.h b/ui/views/controls/menu/menu_runner.h
index f88d2aadce0a3458253775a3d21c690d01b40385..abba98e9dd4095862b385ff57b26a6b49f3e2789 100644
--- a/ui/views/controls/menu/menu_runner.h
+++ b/ui/views/controls/menu/menu_runner.h
@@ -85,6 +85,10 @@ class VIEWS_EXPORT MenuRunner {
     // the caller is responsible for closing the menu upon completion of the
     // drag-and-drop.
     NESTED_DRAG = 1 << 5,
+
+    // Menu with fixed anchor position, so |MenuRunner| will not attempt to
+    // adjust the anchor point. For example the context menu of shelf item.
+    FIXED_ANCHOR = 1 << 6,
   };
 
   // Creates a new MenuRunner, which may use a native menu if available.