Convert the RSS extension to event pages to avoid a dedicated background process.

chrome/test/data/extensions/subscribe_page_action/background.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// A dictionary keyed off of tabId that keeps track of data per tab (for
-// example what feedUrl was detected in the tab).
-var feedData = {};
-
-chrome.extension.onRequest.addListener(function(request, sender) {
+chrome.extension.onMessage.addListener(function(request, sender) {
   if (request.msg == "feedIcon") {
     // First validate that all the URLs have the right schema.
     var input = [];
     for (var i = 0; i < request.feeds.length; ++i) {
       var a = document.createElement('a');
       a.href = request.feeds[i].href;
       if (a.protocol == "http:" || a.protocol == "https:") {
         input.push(request.feeds[i]);
       } else {
         console.log('Warning: feed source rejected (wrong protocol): ' +
                     request.feeds[i].href);
       }
     }
 
     if (input.length == 0)
       return;  // We've rejected all the input, so abort.
 
     // We have received a list of feed urls found on the page.
     // Enable the page action icon.
-    feedData[sender.tab.id] = input;
+    localStorage.setItem(sender.tab.id, JSON.stringify(input));
     chrome.pageAction.setTitle(
       { tabId: sender.tab.id,
         title: chrome.i18n.getMessage("rss_subscription_action_title")
       });
     chrome.pageAction.show(sender.tab.id);
   } else if (request.msg == "feedDocument") {
     // We received word from the content script that this document
     // is an RSS feed (not just a document linking to the feed).
     // So, we go straight to the subscribe page in a new tab and
     // navigate back on the current page (to get out of the xml page).
     // We don't want to navigate in-place because trying to go back
     // from the subscribe page takes us back to the xml page, which
     // will redirect to the subscribe page again (we don't support a
     // location.replace equivalant in the Tab navigation system).
     chrome.tabs.executeScript(sender.tab.id,
         { code: "if (history.length > 1) " +
                  "history.go(-1); else window.close();"
         });
     var url = "subscribe.html?" + encodeURIComponent(request.href);
     url = chrome.extension.getURL(url);
     chrome.tabs.create({ url: url, index: sender.tab.index });
   }
 });
 
 chrome.tabs.onRemoved.addListener(function(tabId) {
-  delete feedData[tabId];
+  localStorage.removeItem(tabId);
 });