new chromium api of widget

a new added api of widget functioning as tabs in chromium.
This is what I have design:
Number of windows open and tabs(in BadgeText) in each window including
titles, url and selected tab(here I use red font).
Except your requirements, you can also click title in pupup and switch
to different tab.Because I think this will make this extension more
meaningful. So I add 'id' in dictionary Tab of widget.idl.