chrome.js

// main.html

<frameset rows="50,*">
  <frame src="nav_bar.html" />
  <frame src="http://www.zoodles.com/" />
</frameset>

// background.html

chrome.extension.onRequest.addListener(function(request, sender, sendResponse) {
  if( sender.tab && request.url ) {
    console.log( 'Document location is = ' + request.url );
    sendResponse({is_blocked: false});
  }
});

// content_script.html

chrome.extension.sendRequest({url: document.location}, function(response) {
  console.log(response.is_blocked);
});

// manifest.json

{
  ...
  "permissions": [
    "tabs",
    "*://*/*"
  ],
  "content_scripts": [
    {
      ...
      "all_frames": true
    }
  ]
}

// console output:

Unsafe JavaScript attempt to access frame with URL chrome-extension://<ID HERE>/app/main.html from frame with URL http://www.zoodles.com/parent/kids/5530/video_mail. Domains, protocols and ports must match.