Refactored the abstraction layer to address prerendered pages on Safari caused by leaky abstraction

popup.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 var backgroundPage = ext.backgroundPage.getWindow();
 var imports = ["require", "extractHostFromURL", "openOptions"];
 for (var i = 0; i < imports.length; i++)
   window[imports[i]] = backgroundPage[imports[i]];
 
 var Filter = require("filterClasses").Filter;
 var FilterStorage = require("filterStorage").FilterStorage;
 var Prefs = require("prefs").Prefs;
 var isWhitelisted = require("whitelisting").isWhitelisted;
 
-var tab = null;
+var page = null;
 
 function init()
 {
-  // Mark page as local to hide non-relevant elements
-  ext.windows.getLastFocused(function(win)
+  ext.pages.query({active: true, lastFocusedWindow: true}, function(pages)
   {
-    win.getActiveTab(function(tab)
+    page = pages[0];
+
+    // Mark page as local to hide non-relevant elements
+    if (!page || !/^https?:\/\//.test(page.url))
+      document.body.classList.add("local");
+
+    // Ask content script whether clickhide is active. If so, show cancel button.
+    // If that isn't the case, ask background.html whether it has cached filters. If so,
+    // ask the user whether she wants those filters.
+    // Otherwise, we are in default state.
+    if (page)
     {
-      if (!/^https?:\/\//.exec(tab.url))
-        document.body.classList.add("local");
-    });
+      if (isWhitelisted(page.url))
+        document.getElementById("enabled").classList.add("off");
+
+      page.sendMessage({type: "get-clickhide-state"}, function(response)
+      {
+        if (response && response.active)
+          document.body.classList.add("clickhide-active");
+      });
+    }
   });
 
   // Attach event listeners
   document.getElementById("enabled").addEventListener("click", toggleEnabled, false);
   document.getElementById("clickhide").addEventListener("click", activateClickHide, false);
   document.getElementById("clickhide-cancel").addEventListener("click", cancelClickHide, false);
   document.getElementById("options").addEventListener("click", function()
   {
     openOptions();
   }, false);
 
   // Set up collapsing of menu items
   var collapsers = document.getElementsByClassName("collapse");
   for (var i = 0; i < collapsers.length; i++)
   {
     var collapser = collapsers[i];
     collapser.addEventListener("click", toggleCollapse, false);
     if (!Prefs[collapser.dataset.option])
       document.getElementById(collapser.dataset.collapsable).classList.add("collapsed");
   }
-
-  // Ask content script whether clickhide is active. If so, show cancel button.
-  // If that isn't the case, ask background.html whether it has cached filters. If so,
-  // ask the user whether she wants those filters.
-  // Otherwise, we are in default state.
-  ext.windows.getLastFocused(function(win)
-  {
-    win.getActiveTab(function(t)
-    {
-      tab = t;
-      if (isWhitelisted(tab.url))
-        document.getElementById("enabled").classList.add("off");
-
-      tab.sendMessage({type: "get-clickhide-state"}, function(response)
-      {
-        if (response && response.active)
-          document.body.classList.add("clickhide-active");
-      });
-    });
-  });
 }
 window.addEventListener("DOMContentLoaded", init, false);
 
 function toggleEnabled()
 {
   var enabledButton = document.getElementById("enabled")
   var disabled = enabledButton.classList.toggle("off");
   if (disabled)
   {
-    var host = extractHostFromURL(tab.url).replace(/^www\./, "");
+    var host = extractHostFromURL(page.url).replace(/^www\./, "");
     var filter = Filter.fromText("@@||" + host + "^$document");
     if (filter.subscriptions.length && filter.disabled)
       filter.disabled = false;
     else
     {
       filter.disabled = false;
       FilterStorage.addFilter(filter);
     }
   }
   else
   {
     // Remove any exception rules applying to this URL
-    var filter = isWhitelisted(tab.url);
+    var filter = isWhitelisted(page.url);
     while (filter)
     {
       FilterStorage.removeFilter(filter);
       if (filter.subscriptions.length)
         filter.disabled = true;
-      filter = isWhitelisted(tab.url);
+      filter = isWhitelisted(page.url);
     }
   }
 }
 
 function activateClickHide()
 {
   document.body.classList.add("clickhide-active");
-  tab.sendMessage({type: "clickhide-activate"});
+  page.sendMessage({type: "clickhide-activate"});
 
   // Close the popup after a few seconds, so user doesn't have to
   activateClickHide.timeout = window.setTimeout(ext.closePopup, 5000);
 }
 
 function cancelClickHide()
 {
   if (activateClickHide.timeout)
   {
     window.clearTimeout(activateClickHide.timeout);
     activateClickHide.timeout = null;
   }
   document.body.classList.remove("clickhide-active");
-  tab.sendMessage({type: "clickhide-deactivate"});
+  page.sendMessage({type: "clickhide-deactivate"});
 }
 
 function toggleCollapse(event)
 {
   var collapser = event.currentTarget;
   Prefs[collapser.dataset.option] = !Prefs[collapser.dataset.option];
   collapser.parentNode.classList.toggle("collapsed");
 }