If you don't like the behavior, there are ways to change it yourself:
* Install flash blocking plugin * Enable click-to-play * Install a plugin that disabled auto-play (at least for youtube, don't know about a netflix one) * Put the computer to sleep/hibernate * Turn off speakers * Turn off the computer ... * Close the netflix tab
There are many many options. If you don't like closing out chrome because you'll be missing your tabs, then use a plugin like "Session Manager" and then save your currently open tabs, and then close Chrome.
I don't think this is a bug. I think it works just fine.
Heck, I don't know which setting I have but if chrome crashes or if I restart my computer without nicely closing chrome, Chrome will re-open upon boot BUT it'll open a new blank tab with a bar at the top that says something like "Chrome didn't shut down properly. Do you want to restore your old tabs?" ... that works extremely well.