One bad thing about Google Chrome is you can accidentally close a window in Chrome with many tabs without any warning from Chrome. The way to reopen it is CTRL+SHIFT+T (surprisingly is the same command as reopen last tab!). You could also look for a Chrome extension such as Windows Close Protector
From Google Chrome help:
If you accidentally close a tab or window, you can easily recover it using the keyboard shortcut Crtl+Shift+T (Mac: ⌘-Shift-T) or follow the steps below:
- Click the Chrome menu on the browser toolbar.
- Select Recent Tabs.
- Select the desired tab from the list under “Recently closed”.