In the extension code you can use any chrome.*
API if you decalared the required permissions. In addition, some API's works only from background pages, and some API's works only from content scripts.
You can use most of chrome.tabs
methods declaring any permissions. Now we focus on chrome.tabs.create
Note: The new tab will be opened without any popup
warning.
chrome.tabs.create({
url:"http://stackoverflow.com",
selected:false // We open the tab in the background
})
You can learn more about tab object, in the official chrome developer