Fix bug in browser action overflow container

Fix a bug where reording actions in the browser action overflow container can
cause them all to become visible.

BUG=414177

Review URL: https://codereview.chromium.org/570403002

Cr-Commit-Position: refs/heads/master@{#295108}

chrome/browser/ui/views/extensions/browser_action_overflow_menu_controller.cc

@@ -239,7 +239,7 @@ int BrowserActionOverflowMenuController::OnPerformDrop(
 
   // If the extension was moved to the overflow menu from the main bar, notify
   // the owner.
-  if (drop_index >= owner_->VisibleBrowserActions())
+  if (drop_data.index() < owner_->VisibleBrowserActions())
     owner_->NotifyActionMovedToOverflow();
 
   if (for_drop_)