The extensions overflow bar in the main app menu is a turducken, and not the tasty kind. It is:
 - A BrowserActionsContainer
 - Wrapped in a ScrollView::Viewport
 - Wrapped in a ScrollView
 - Which is an ExtensionToolbarMenuView
 - Wrapped in a MenuItemView

The problem is that there is "container" logic built into MenuItemView, which only seems to apply to this one case, but which doesn't position the ExtensionToolbarMenuView correctly. To fix this, ExtensionToolbarMenuView::Layout() changes both its size and position within its parent on Layout(). This means the order in which Layout() is called on these controls affects whether the inner control is positioned properly.

This is an antipattern and should be fixed. No view should ever move itself during layout.

I have put in a temporary fix to make the container behavior of MenuItemView call the child view's Layout() explicitly, but I want this to be fixed in a more robust way.