title: Message isn't passed between background.html and popup.html
body: <p>I'm trying to pass data that is saved in sessionStorage from background.html to popup.html</p>
  
  <p>background.html:</p>
  
  <pre><code>chrome.extension.onRequest.addListener(function(request, sender, sendResponse) {
    data = sessionStorage.getItem(request.tabId);
    alert(data);
    sendResponse({ data: data });
  });
  </code></pre>
  
  <p>and in popup.html:</p>
  
  <pre><code>chrome.tabs.getSelected(null, function(tab) {
    chrome.extension.sendRequest({ tabId: tab.id }, function(response) { 
      alert(response.data);
    });
  });
  </code></pre>
  
  <p>The popup is opened by a pageAction button, when I click the button I get an alert box with "null" on the popup and then an alert box with the data that I stored in sessionStorage on the background!</p>
  
  <p>Any ideas how to fix this?</p>