Chrome Extension to Compare Web Page Data with XML File and Return Result

I think this is somewhat basic for someone who knows what they are doing. Job is for a vacation rentals website who has an XML sitemap with a big list of destinations. Extension needs to crawl active web page and determine if content is about a particular region or city. If it is determined that the page mentions the region and/or city more than once, and there is a website URL match, the extension icon should indicate that a match has occurred. Clicking on the extension icon should produce a small drop down that says something like "Stay Here"; clicking the drop down will send people to the relevant page. Will consider any recommended upgrades to the extension.