Messages from frame.js:

1. DOMContentLoaded: ...
2. pageshow: ...
3. load: ...
4. unload: ...

Messages from main.js:

1. DOMContentLoaded: ...
2. pageshow: ...
3. load: ...
4. unload: ...

Expected results:

1. DOMContentLoaded: Success!
2. pageshow: Success!
3. load: Success!
4. unload: Success!