var domainExceptions = {};

chrome.webRequest.onBeforeRequest.addListener(
  function(info) {
    var blocking = checkForPeevskiDomain(info.url);
    if (blocking !== false) {
      var date = new Date();
      var time = date.getTime();
                        var warning_page = blocking.reason == 'domain' ? 'warning.html' : 'warning_fb.html';
      if (domainExceptions[blocking.url] === undefined || time > domainExceptions[blocking.url]) {
        return {redirectUrl: chrome.extension.getURL(warning_page) + '?' + encodeURIComponent(info.url)};
      }
    }
    return null;
  },
  // filters
  {
    urls: [
      "http://*/*",
      "https://*/*"
    ],
    types: [ "main_frame" ]
  },
  // extraInfoSpec
  [ "blocking" ]
);

chrome.runtime.onMessage.addListener(
  function(request, sender, sendResponse) {
    if (request.allowCurrentUrl) {
      var url    = request.allowCurrentUrl;
      var blocking = checkForPeevskiDomain(url);
      var date   = new Date();
      var time   = date.getTime();
      domainExceptions[blocking.url] = time + 10 * 60 * 1000;

      chrome.tabs.getSelected(null, function (tab) {
        chrome.tabs.update(tab.id, {url: url});
      });
    }
  }
);

var domainExceptions = {};

chrome.webRequest.onBeforeRequest.addListener(
  function(info) {
    var blocking = checkForPeevskiDomain(info.url);
    if (blocking !== false) {
      var date = new Date();
      var time = date.getTime();
      var warning_page = blocking.reason == 'domain' ? 'warning.html' : 'warning_fb.html';
      if (domainExceptions[blocking.url] === undefined || time > domainExceptions[blocking.url]) {
        return {redirectUrl: chrome.extension.getURL(warning_page) + '?' + encodeURIComponent(info.url)};
      }
    }
    return null;
  },
  // filters
  {
    urls: [
      "http://*/*",
      "https://*/*"
    ],
    types: [ "main_frame" ]
  },
  // extraInfoSpec
  [ "blocking" ]
);

chrome.runtime.onMessage.addListener(
  function(request, sender, sendResponse) {
    if (request.allowCurrentUrl) {
      var url    = request.allowCurrentUrl;
      var blocking = checkForPeevskiDomain(url);
      var date   = new Date();
      var time   = date.getTime();
      domainExceptions[blocking.url] = time + 10 * 60 * 1000;

      chrome.tabs.getSelected(null, function (tab) {
        chrome.tabs.update(tab.id, {url: url});
      });
    }
  }
);

Fix bad indentation in chrome/background.js