Usage:

This extensions brings an icon in the URL (address) bar which shows "v4" when connected to an host via IPv4 and "v6" when connected via IPv6. (Shows "v?" when local or undetermined).
Hover over the icon to see the actual IP to which you just made a request.
Click the icon to look up host's IP on domaintools in a new Tab. (Only when IP is not undefined.)

Please acknowledge that the showed IP is relevant to the "main_frame" (the main webpage structure) of the host you connected to, and that your browser made at least twice or three times more requests to different hosts and IP's to draw the page your are seeing. That is to say, connecting to a page means you connect seamlessly to many other services and other servers. ChangeLog

0.2a Hotfix from 24/08/17

Fixed: removed previously added unnecessary webNavigaton permission. (Tried stuff and forgot to remove it)
activeTab permission was also unnecessary.
Fixed: icon and IP not updated when local scheme such as about:about. IP is now set to "Undefined" in such cases.
The domaintools lookup when clicking the icon is only performed if the IP of host if different from "Undefined".

0.2 Version from 22/08/17

Code and style reformat by yfdyh000.
webRequest event changed from onCompleted to onHeadersReceived by gloomy-ghost.
Fixed: issue where icon icon disappeared after clicking a link.
Now using a map to keep track of 'host' and 'ip' and 'ipProtocolVersion' for each tabs.
New Feature: when clicking icon, opens a tab to look up IP on domaintools.

0.1 Version from 17/08/17

Initial version.
Icons for IPv4 and IPv6.
Shows IP as tooltip.