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

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

Index: chrome/test/data/extensions/subscribe_page_action/background.js
===================================================================
--- chrome/test/data/extensions/subscribe_page_action/background.js	(revision 190361)
+++ chrome/test/data/extensions/subscribe_page_action/background.js	(working copy)
@@ -2,11 +2,7 @@
 // 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 = [];
@@ -26,7 +22,7 @@
 
     // 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")
@@ -52,5 +48,5 @@
 });
 
 chrome.tabs.onRemoved.addListener(function(tabId) {
-  delete feedData[tabId];
+  localStorage.removeItem(tabId);
 });