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..23df1044a02b88d195299e977e0c96516ae09775 100644
--- a/ui/views/controls/menu/menu_runner.h
+++ b/ui/views/controls/menu/menu_runner.h
@@ -85,6 +85,9 @@ class VIEWS_EXPORT MenuRunner {
     // the caller is responsible for closing the menu upon completion of the
     // drag-and-drop.
     NESTED_DRAG = 1 << 5,
+
+    // The context menu of the shelf item.
+    SHELF_CONTEXT_MENU = 1 << 6,

[sadrul, 2017/05/10 01:25:40]

Can you call this FIXED_ANCHOR, or something like that? Essentially, it's a hint
to MenuRunner so that it does not attempt to figure out the anchor-position by
itself. Because views should not need to know about 'shelf' etc.

   };
 
   // Creates a new MenuRunner, which may use a native menu if available.