Chrome open tabs and open chrome windows

You only have access to the list of running processes?
Will be hard to tell since chrome opens a bunch of processes for tabs, extensions, add-ons, just because

you may have more luck in the users app data directory.

You might be able to determine how many tabs were open from the "Current Tabs", "Current Session", "Last Tabs" and “Last Session” files. These are located in the Chrome profile folder e.g. C\Users\{Username}\AppData\Local\Google\Chrome\User Data\Default

Here's a detailed blog post on how to parse the files
https://digitalinvestigation.wordpress.com/2012/09/03/chrome-session-and-tabs-files-and-the-puzzle-of-the-pickle/

Guys,thanks for the valuable insights. D