javascript - chrome web extention not showing popup -

i saw youtube video of how create basic chrome extension , loaded unpacked extension browser does't give popup.here code

{     "name":"facebook",     "version":"1.0",     "description":"my facebook profile",     "manifest_version":2,     "browser_action":{         "default_icon":"google-plus-red-128.png",         "popup":"hello.html"     } } 

and here html file

<h2>hello world</h2> 

the correct manifest keyword browser action popup "default_popup", not "popup". change that, , should fine.