Close a pop-up window in Chrome during a test

We use this to close unexpected windows "Leave This Page?"

The first one is is run as an event handler from event OnWebBeforeNavigate.

function Test_Complete_Test_Run_Events_OnWebBeforeNavigate(Sender, WebBrowser, URL)
{
        // Check for the presence of the "Leave This Page?" popup
        
        
        Close_Leave_Site_popup();
}


function Close_Leave_Site_popup()
{
        var Max_Wait_Time_ms = 500;

               // Check for Edge unexpected window...
        if(Aliases.browser.Application_Main_Page.Browser_Leave_Site_popup.Leave_button.WaitProperty("Exists", true, Max_Wait_Time_ms) == true)
        {
                Aliases.browser.Application_Main_Page.Browser_Leave_Site_popup.Leave_button.Click();
                Log.Message("MS Edge: UNEXPECTED WINDOW closed");
        }
        
        // Check for IE unexpected window...
        if(Aliases.browser_IE.Application_Main_Page.Browser_Confirm_popup.Leave_This_Page_button.WaitProperty("Exists", true, Max_Wait_Time_ms) == true)
        {
                Aliases.browser_IE.Application_Main_Page.Browser_Confirm_popup.Leave_This_Page_button.Click();
                Log.Message("IE: UNEXPECTED WINDOW closed");
        }

}

And as AmulyaT  said you can obtain the mapping by recording or spying the window and mapping it manually or using a suitable template.

We also get Java popups which we clear using a simple "close" or  refreshing the page.