Code review comment for lp:~paulliu/unity-mir/logout

After discussion with some people, I found that we actually don't have any specs or documents about it.
All of it is being defined "while coding" it.
Here's the interface in unity7.
http://pastebin.ubuntu.com/7231097/
It is in shutdown/SessionDBusManager.cpp in lp:unity.

So the thing is "indicator-session" will call the method "RequesetLogout". And the ApplicationManager will see if we have any important apps that inhibits the logout action ( while I don't think there's such app in Phone right now ) and then send out the signal "LogoutRequested" with a boolean to indicate if there's such apps.
And then Unity shell should receive that signal and display a dialog for the user to decide to logout or not.
If the user decide to logout, then unity shell call the method "Logout" and we have to shutdown all the app. After that, we signal the shell to shut itself.

I've fix some unclear naming. Not sure if we have a better name for logoutReady and unityLogout.
In unity7, When Logout is called, it forwards this method to org.gnome.SessionManager and some fallbacks