Issue 3880 - Improve behavior of Safari content blocker option

options.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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
@@ skipping 700 matching lines @@
       });
     });
     ext.backgroundPage.sendMessage(
     {
       type: "app.get",
       what: "features"
     },
     function(features)
     {
       hidePref("show_devtools_panel", !features.devToolsPanel);
-      hidePref("safari_contentblocker", !features.safariContentBlocker);
+
+      // Only show option to switch between Safari Content Blockers
+      // and event based blocking if both are available.
+      hidePref("safari_contentblocker", !(
+        features.safariContentBlocker &&
+        "canLoad" in safari.self.tab &&
+        "onbeforeload" in Element.prototype
+      ));
     });
 
     var filterTextbox = document.querySelector("#custom-filters-add input");
     placeholderValue = getMessage("options_customFilters_textbox_placeholder");
     filterTextbox.setAttribute("placeholder", placeholderValue);
     function addCustomFilters()
     {
       var filterText = filterTextbox.value;
       sendMessageHandleErrors(
       {
@@ skipping 341 matching lines @@
 
     for (var i = 0; i < shareResources.length; i++)
       checkShareResource(shareResources[i], onResult);
   }
 
   ext.onMessage.addListener(function(message)
   {
     switch (message.type)
     {
       case "app.respond":
-        if (message.action == "addSubscription")
+        switch (message.action)
         {
-          var subscription = message.args[0];
-          var dialog = E("dialog-content-predefined");
-          dialog.querySelector("h3").textContent = subscription.title || "";
-          dialog.querySelector(".url").textContent = subscription.url;
-          openDialog("predefined");
+          case "addSubscription":
+            var subscription = message.args[0];
+            var dialog = E("dialog-content-predefined");
+            dialog.querySelector("h3").textContent = subscription.title || "";
+            dialog.querySelector(".url").textContent = subscription.url;
+            openDialog("predefined");
+            break;
+          case "safariRestartRequired":
+            E("restart-safari").setAttribute("aria-hidden", !message.args[0]);
+            break;
         }
         break;
       case "filters.respond":
         onFilterMessage(message.action, message.args[0]);
         break;
       case "prefs.respond":
         onPrefMessage(message.action, message.args[0]);
         break;
       case "subscriptions.respond":
         onSubscriptionMessage(message.action, message.args[0]);
         break;
     }
   });
 
   ext.backgroundPage.sendMessage(
   {
     type: "app.listen",
-    filter: ["addSubscription"]
+    filter: ["addSubscription", "safariRestartRequired"]
   });
   ext.backgroundPage.sendMessage(
   {
     type: "filters.listen",
     filter: ["added", "loaded", "removed"]
   });
   ext.backgroundPage.sendMessage(
   {
     type: "prefs.listen",
     filter: ["notifications_ignoredcategories", "notifications_showui",
         "safari_contentblocker", "show_devtools_panel",
         "shouldShowBlockElementMenu"]
   });
   ext.backgroundPage.sendMessage(
   {
     type: "subscriptions.listen",
     filter: ["added", "disabled", "homepage", "lastDownload", "removed",
         "title"]
   });
 
   window.addEventListener("DOMContentLoaded", onDOMLoaded, false);
 })();