Chrome Extension

I need a Chrome Extension that can detect if a textbox has been changed or not in a iframe every time the enter key has been hit inside a dynamic iframe which means the iframe content keeps changing every time the enter key is hit and all the content is in a iframe. So every time the enter key is hit inside the iframe I need the Extension to keep track of it if the textbox content has been changed at all or not so in a popup for the Extension it would show 1/1 100 percent for no changes then 1/2 50 percent if changes were made to the textbox and so on. I would also like the option in the popup to be able to reset the tracking back to 0/0 0 percent and once again start it.