Add the reason for deactivation to the 'deactivate_plugin' hook.

[merlijnvanlent]

To be able to check if a plugins was disabled by a user action or because of the 'validate_active_plugins' check that is done on when visiting the plugins.php page would be great from a management perspective. Many WordPress installations have some required plugins which are not necessary for the site to work but do need to be active for one reason or another. This enables the option to notify the admin when a plugin gets disabled by accident because of a failed updated or any other reason.

[johnbillion]

This is a good idea.