Firefox has an inbuilt feature that saves the sessions (i.e tabs that are open) when closing the browser. When its restarted, all the previously unclosed tabs are opened again. Guess what, Google Chrome has also got it. Here's how to enable it.
1. Click the Tools icon on the top-right of the browser (Its near the address bar). Click on Options (If you are on Linux, it should be Preferences).
2. A new window pops up. Under the Basics tab, select the "Reopen the pages that were open last" option.
That's all. Now Google Chrome will preserve the tabs when closing and open them again when started.
An interesting option is the third one which allows you to choose which pages to open when starting Chrome.